Description
The Assignment (2–4 pages):
First, summarize the material in the text and describe the biological basis of sexual orientation, including the brain regions, neurotransmitters, and hormones that may be associated with sexual orientation. Also consider any developmental factors that may influence later sexual orientation. Include any relevant anatomical or physiological markers that seem to be associated with a particular sexual orientation.
Summarize your article on the biological basis of sexual orientation in enough detail that your reader will understand what was done in the study and what the results of the study were (similar to the articles you found in BioPsychology.com in the first week).
Finally, develop and describe a high-level overview of an educational program about the biological basis of sexual orientation. This should be appropriate to present to a middle school biology class. What would you include in this educational program? What would you not include in the educational program? How would you convey the ideas you have described in this week’s Assignment in a way that would not offend your audience, but would also minimize the giggles of young teenagers?
Support your Assignment with specific references to all resources used in its preparation. You should include in-text citations in the body of your Assignment as well as complete references in APA format at the end of your Assignment.
MY SELECTED ARTICLE: Prenatal Exposure to Progesterone Affects Sexual Orientation
Unformatted Attachment Preview
Arch Sex Behav (2017) 46:1239–1249
DOI 10.1007/s10508-016-0923-z
ORIGINAL PAPER
Prenatal Exposure to Progesterone Affects Sexual Orientation
in Humans
June M. Reinisch1,2,3 • Erik Lykke Mortensen3,4 • Stephanie A. Sanders1,5
Received: 18 June 2013 / Revised: 15 December 2016 / Accepted: 15 December 2016 / Published online: 3 April 2017
Springer Science+Business Media New York 2017
Abstract Prenatal sex hormone levels affect physical and behavioralsexualdifferentiationinanimalsandhumans.Althoughprenatal hormones are theorized to influence sexual orientation in
humans, evidence is sparse. Sexual orientation variables for 34
prenatally progesterone-exposed subjects (17 males and 17
females) were compared to matched controls (M age = 23.2
years). A case–control double-blind design was used drawing
on existing data from the US/Denmark Prenatal Development
Project. Index cases were exposed to lutocyclin (bioidentical
progesterone = C21H30O2;MW:314.46)andnootherhormonal
preparation. Controls were matched on 14 physical, medical,
and socioeconomic variables. A structured interview conducted by a psychologist and self-administered questionnaires
were used to collect data on sexual orientation, self-identification,attractiontothesameandothersex,andhistoryofsexual
behavior with each sex. Compared to the unexposed, fewer
exposed males and females identified as heterosexual and more
of them reported histories of same-sex sexual behavior, attraction to the same or both sexes, and scored higher on attraction to
males. Measures of heterosexual behavior and scores on attractiontofemalesdid not differsignificantly byexposure. Wecon& June M. Reinisch
[email protected]
1
The Kinsey Institute for Research in Sex, Gender and
Reproduction, Indiana University, Morrison Hall 313,
Bloomington, IN 47405, USA
2
The Museum of Sex, New York, NY, USA
3
Institute of Preventive Medicine, Copenhagen University
Hospital, Copenhagen, Denmark
4
Department of Public Health, University of Copenhagen,
Copenhagen, Denmark
5
Department of Gender Studies, Indiana University,
Bloomington, IN, USA
clude that, regardless of sex, exposure appeared to be associatedwithhigherratesofbisexuality.Prenatalprogesteronemaybe
an underappreciated epigenetic factor in human sexual and psychosexual development and, in light of the current prevalence of
progesterone treatment during pregnancy for a variety of pregnancy complications, warrants further investigation. These data
ontheeffectsofprenatalexposuretoexogenousprogesteronealso
suggest a potential role for natural early perturbations in progesterone levels in the development of sexual orientation.
Keywords Sexual orientation
Prenatal progesterone exposure Bisexuality
Sexual behavior
Introduction
Although prenatal gonadal hormones have been theorized to
influence sexual orientation in humans, other than recent
research using a surrogate measure (2D:4D digit ratio) for prenatalandrogenexposure(Hiraichi,Sasaki,Shikishima,&Ando,
2012; Wong & Hines, 2015), evidence from studies of exogenous hormone exposure is sparse (Adkins-Regan, 1988; Ellis &
Ames, 1987; Gooren, 2006; Hines, 2011; Hines, Constantinescu, & Spencer, 2015; Meyer-Bahlburg, 1984). Despite relatively frequent current administration of exogenous progesterone to pregnant women with a variety of clinical problems,
even less attention has been paid to the possible role of prenatal
exposure to progesterone on any aspect of human sexual and
psychosexual development (Kester, Green, Finch, & Williams,
1980; Reinisch, Ziemba-Davis, & Sanders, 1991; Sanders &
Reinisch, 1985; Wagner, 2008). Perhaps this is due to the elevated levels of natural progesterone present during gestation leading to the assumption that additional exogenous doses would not
affect these aspects of development.
123
1240
The prenatal hormone or neuroandrogenic theory of sexual
orientation (Ellis & Ames, 1987; Gooren, 2006; Hines, 2010;
Meyer-Bahlburg, 1984) assumes that heterosexuality is an inherent part of ‘‘normal’’ sexual differentiation and that homosexuality (as evidenced by self-identification, same-sex sexual
behavior, or attraction/desire) is a result of perturbations in the
typical prenatal hormone environment. Specifically, the theory
suggests that homosexuality is the result of insufficient prenatal
androgen exposure or action in males and excess prenatal androgen exposure in females during sensitive periods of early development. Thus, homosexuality is viewed as some degree of feminization and/or demasculinization of males and of masculinization and/or defeminization of females. Bisexuality in humans
is often thought of as‘‘partial homosexuality’’or as moving away
from‘‘exclusive heterosexuality’’toward a middle point along a
bipolar unidimensional continuum between exclusive heterosexuality and exclusive homosexuality (Kinsey, Pomeroy, &
Martin, 1948). This bipolar Kinsey scale model implies a trade-off between heterosexuality and homosexuality—the more homosexual, the less heterosexual (see Sanders, Reinisch, & McWhirter,
1990).
For ethical reasons, support for the formative role of prenatal
sex hormones in the development of sexual orientation is based
primarily on experiments with animals (Adkins-Regan, 1988;
Balthazart, 2011; Hines, 2011; Meyer-Bahlburg, 1984), a few
clinical studies of humans whose prenatal hormone environments were altered by metabolic anomalies (Cohen-Bendahan,
van de Beek, & Berenbaum, 2005; Hines, 2004, 2010, 2011;
Jordan-Young, 2012; Meyer-Bahlburg, 1984), or maternal medical treatment with estrogenic compounds during gestation
(Meyer-Bahlburget al., 1995), and most recently thestudies using
digit ratio measures to reflect the prenatal gonadal hormone
environment (Grimbos, Dawood, Burris, Zucker, & Puts, 2010;
Wong & Hines, 2015). Critiques (Adkins-Regan, 1988; Balthazart, 2011; Hines, 2011; Meyer-Bahlburg, 1984; Valla & Ceci,
2011) of this perspective and its putative supportive animal
research include: (1) conflation of heterotypic sexual behavior in
animals (i.e., accepting mounts in males or mounting by females)
and human homosexuality (e.g., the male rat who mounts another
maleisnotconsidered‘‘homosexual,’’whilethemountedmaleis);
(2) limitations in extrapolating from phylogenetically distant animals to humans; and (3) the focus on copulatory (consummatory)
behaviorsinanimalmodelsratherthanmatepreference(appetitive)
behaviors. Additionally, studies in humans are generally limited or
complicated by small sample size; inadequate or inappropriate
matches or‘‘control’’groups; insufficient assessment of sexual orientation or hormone exposure; mixed hormonal exposures; exogenous exposure to synthetic rather than naturally occurring hormones;alterationsofgenitalanatomyrelatedtohormoneexposure;
confounds with other metabolic and physical correlates of intersex
conditions; and/or simultaneous exposures to other treatment com-
123
Arch Sex Behav (2017) 46:1239–1249
pounds. Nonetheless, there is substantial evidence that early exposure to sex hormones influences anatomical, physiological, and
sexually dimorphic behavioral development in animals and
humans(Cohen-Bendahanetal.,2005;Reinisch,1974;Reinisch&
Sanders, 1984, 1987; Reinisch et al., 1991). Thus, investigation of
theroleofprenatalsexhormonesinthedevelopmentofhumansexual orientation incorporating more effective controls is warranted.
It has been suggested that the potential role of progesterone in
mammalian sexual differentiation and development has been
insufficiently investigated (Dodd, Jones, Flenady, Cincotta, &
Crowther, 2013; Wagner, 2008). Although androgenic, estrogenic, and antiandrogenic compounds have received attention
(including synthetic progestins, some of which have androgenic
effects), there has been relatively little examination of the role of
progesterone, despite its demonstrated antiandrogenic and antiestrogenic effects on some systems (Dorfman, 1967; Sanders &
Reinisch,1985).Progesteroneandsyntheticprogestinsarecommonly prescribed during early pregnancy for luteal phase support during in vitro fertilization and for threatened abortion
(Aboulghar, 2009; Baker et al., 2014, Palagiano et al., 2004) and
later in pregnancy for prevention of premature birth and low
birth weight (da Fonseca, Bittar, Damião, & Zugaib, 2009).
Few studies have examined the long-term physical and
behavioral outcomes of either naturally occurring or synthetic
progestin exposure in humans (Cohen-Bendahan et al., 2005;
Hartwig et al., 2014; Hines, 2004, 2010; Northen et al., 2007;
Reinisch, 1974, Reinisch & Sanders, 1984, 1987; Reinisch et al.,
1991). Maternal intake of synthetic progestins and/or progesterone during pregnancy has been found to be associated with
increased hypospadias (urinary opening on the underside of the
penis instead of the tip) risk in males (Carmichael et al., 2005;
Dorfman, 1967; Silver, Rodriguez, Chang, & Gearhart, 1999)
and alteration of some sex-differentiated behavior patterns in
male and female offspring (Cohen-Bendahan et al., 2005; Ehrhardt, Grisanti, & Meyer-Bahlburg, 1977; Kester et al., 1980;
Reinisch, 1974, 1977, 1981; Reinisch & Karow, 1977; Reinisch
& Sanders, 1984, 1987; Reinisch et al., 1991; Sanders & Reinisch, 1985).
One of these studies examined the effects of ‘‘natural’’ progesterone on sex/gender development (Kester et al., 1980). It
included 10 men (19–24 years) exposed prenatally to natural
progesterone alone and a control group matched on date of birth,
age of mother, and, in most cases, prior numbers of siblings.
Progesterone-exposed subjects‘‘tended to recall boyhood behaviors which departed from the conventional male mode toward
‘femininity’’’and those subjects exposed to higher doses scored
lower on the Bem Sex-Role Inventory Masculine scale and lower
on the Feminine scale. A more recent study of fetal exposure to
prescription drugs and sexual orientation did not find a significant
relationship between maternal reports of progesterone/progestin
exposure and sexual orientation, but the study was limited by its
Arch Sex Behav (2017) 46:1239–1249
reliance on maternal recall of medical treatment often decades
earlier, among other methodological issues (Ellis & Hellberg,
2005).
Inlightofthesefindingsandthedearthofdataontheoffspring
of progesterone-treated pregnancies, we compared data on sexual orientation and attraction from young adults who were
exposed in utero to progesterone (bioidentical progesterone =
C21H30O2; MW: 314.46) via maternal medical treatment to data
from unexposed matched controls. The study employed a case–
control, double-blind, prospective, longitudinal design using
membersofabirthcohortwithmatchingofcasesandcontrolson
14 physical, medical, and socioeconomic variables that were
recorded prenatally or at birth; careful evaluation of prenatal
hormone exposure; and assessment of sexual orientation and
attraction. Based upon the limited animal models and human
research, we hypothesized that progesterone-exposed human
offspring would show more same-sex attraction and behavior
with more exposed subjects identifying as non-heterosexual.
Method
Participants
Data from 34 subjects (17 men and 17 women) prenatally exposed exclusively to lutocyclin and no other hormonal preparation, and their individually matched unexposed controls were
drawn from an existing database, the US/Denmark Prenatal
Development Project (PDP) (Reinisch, Mortensen, & Sanders,
1993). Lutocyclin is identified as progesterone (bioidentical progesterone = C21H30O2; MW: 314.46) in the Danish Physician’s
Desk Reference (Junager & Schleisner, 1963) and was administered during pregnancy to treat cases of potential miscarriage as
indicated by staining or bleeding, abortion imminens (threatened
abortion), or maternal history of repeated miscarriage. Mean age
of the participants at the time of assessment for this study was
23.2 years (SD = 1.4).
Participants were drawn from the Copenhagen Perinatal
Cohort, comprising all 9125 offspring born at the University
Hospital in Copenhagen, Denmark, between 1959 and 1961.
During the establishment of the cohort, demographic, socioeconomic, and medical variables were prospectively recorded
pre-, peri-, and postnatally. Potential participants for the current
study were identified through the available computerized database. Exclusion criteria were: offspring of incest; gestation
length less than 28 weeks; congenital malformation (including
genital ambiguity); Down’s syndrome; maternal history of diabetes,epilepsyorCNSdisorder;maternaltreatmentwiththyroid
medication; maternal psychosis or syphilis; mother less than age
16 at time of delivery; and mother diagnosed with polio,
encephalitis, meningitis, viral pneumonia, or ornithosis during
pregnancy. The original datatape only coded yes/no for drug
1241
exposure in terms of the class of drug administered (hormone,
barbiturate, antiepileptic, etc.) for at least 5 days during each of
six gestational periods, coded into trimesters for these analyses.
Original hospital records for all hormone-exposed cases and
their matched controls were reviewed by our team to confirm
exclusion criteria and to obtain specific information on dosage,
timing, and duration of exposure to all gestational treatments.
All eligible cases were recruited to participate in the PDP. The
overallparticipationrateforthePDPwas87%.Extensivedetails
of the methodology are reported elsewhere (Reinisch et al.,
1993; Reinisch, Sanders, Mortensen, & Rubin, 1995). Participants only knew they were recruited due to their inclusion in the
Danish Perinatal Cohort at birth but were blind as to their exposure status.
Of the 45 cases exposed to lutocyclin in the PDP database, the
34 included here were those exposed to lutocyclin and no other
hormonal preparation, so that any observed effects of lutocyclin
would not be confounded by exposures to other hormones.
Matches were chosen from 271 non-exposed controls selected
from a large pool of similarly evaluated PDP members.
Matching occurred in two stages using 14 variables with
exact matching for sex. The objective of the matching was to
obtain a set of control subjects whose distributions on matching
variableswereascloseaspossibletothedistributionsofexposed
subjects. First, using Mahalanobis metric matching within calipers defined by the estimated propensity score for each exposed
case, the 10 statistically best potential controls were identified
(Rosenbaum & Rubin, 1985a, 1985b) and then the Project
Director (J.M.R.) matched one or two potential controls to each
exposed case for inclusion in the study. Details of the matching
procedure have been published elsewhere (Reinisch et al.,
1993, 1995). Table 1 shows that there were no significant group
differences (exposed vs. unexposed) in the distributions of matching variables.
When the Perinatal Cohort was established, pregnant women
were interviewed as soon as they were enrolled for prenatal care
about whether they were married or single, had planned the
pregnancy at the time of conception, or had attempted abortion
(Villumsen, 1970). For exposed cases, there was one single
mother (2.9%), one unplanned pregnancy (2.9%, not the same
person), and no abortion attempts. For the matched control
sample, 23% of the mothers were single, 44% of the pregnancies
were unplanned, and 12% had attempted abortion. The percentagesfortheoverallcohortwere37,56,and7%,respectively.
It is not surprising that special treatment for pregnancy maintenance was confounded with being married, planning or wanting the pregnancy, and not attempting abortion. Therefore, these
were not used as matching variables. At the time, relatively few
couples were living together without being married and being a
single mother may have presented difficulties. We do not
interpret these potential confounds as potential causative factors
for same-sex (homosexual/bisexual) behavior and attraction. In
thePDPsampleofmorethan550participants,thesethreemater-
123
1242
Arch Sex Behav (2017) 46:1239–1249
Table 1 Distributions of matching variables for prenatally progesterone-exposed and unexposed participants
Matching variable
Exposed
n = 34
Unexposed
n = 34
Statistica
% Maleb
50.0
50.0
na
% Firstborn
61.8
50.0
z = .85
ns
Mean (SD) gestation length (week)
37.76 (3.10)
38.12 (1.80)
t(32)1
ns
Mean (SD) birth weight (g)
31.13 (8.85)
30.99 (5.06)
t(33)1
ns
Mean (SD) birth length (cm)
50.97 (4.66)
50.69 (2.29)
t(33)1
ns
Mean (SD) socioeconomic statusc
6.00 (1.55)
5.94 (1.52)
t(31)1
ns
Mean (SD) breadwinner’s educationd
Mean (SD) mother’s age (year)
3.07 (.78)
30.03 (4.46)
3.06 (.74)
31.15 (5.76)
t(29)1
t(33) = -1.06
ns
ns
p
Mean (SD) father’s age (year)
35.00 (6.03)
33.48 (7.12)
t(32) = 1.04
ns
Mean (SD) PBC 415e
33.85 (17.91)
33.53 (16.12)
t(33)1
ns
Mean (SD) maternal complaint scoref
2.96 (2.48)
3.22 (2.52)
t(33)1
ns
% Severe preeclampsia
3.0
2.9
z=0
ns
% Maternal respiratory illness
2.9
2.9
z=0
ns
Mean (SD) maternal weight gain (kg)/height cubed (m) Wgt/hght
25.52 (9.05)
25.29 (7.35)
t(23)1
ns
Mean (SD) no. of cigarettes/day in third trimester
4.42 (7.01)
5.74 (7.64)
t(32)1
ns
a
na = Not applicable. Unless otherwise noted df = 33
b
Exact match required for sex
c
Family socioeconomic status when the child was 1 year of age. Danish system categorized on an eight-point scale, 1 = lowest, 8 = highest. Pairs were
exactly matched on SES, except for two exposed cases with missing data who were matched to controls with SES = 4
d
Education was categorized on a four-point scale, 1 = remedial instruction, 4 = college
e
The predisposing risk score is a variable in the original cohort datatape. It is a score based on pregravidas factors concerned with the mother’s physical
and emotional state prior to the pregnancy. Information includes such items as whether the mother was married when she conceived, whether she had
previously had an abortion, a miscarriage, a stillbirth, or neonatal death; her age; her weight; and previous history of central nervous system illness,
syphilis, cardiovascular illness, or diabetes. The score indicates that conditions (physical and emotional) were probably ‘‘less than optimum’’ for
conception at the time. For the cohort, the scores range from 0 to 130 and the mean is 29.52
f
The maternal complaint score included the following: severe preeclampsia, hypertension, prescription of diuretics, edema and proteinuria, bleeding/
staining, allergies and treatment with antihistamines, and anemia
nal variables were unrelated to offspring sexual orientation, attraction, or sexual behavior in either sex.
Lutocyclin exposure parameters in the present sample were
asfollows:Meantotaldosagewas915 mg(SD = 1073.54,range
40–5400 mg) with a mean treatment duration of 61 days (SD =
42, range 8–158). Average daily dose was calculated for each
individual by dividing total dosage byduration of treatment.The
group mean of ‘‘average daily dose’’ was 18.41 mg/day. Fortyonepercent(n = 14)wereexposedduringthefirsttrimesteronly,
35% (n = 12) during the first and second trimesters, 17% (n = 6)
during the second trimester only, and 6% (n = 2) during the
second and third trimesters. Table 2 shows detailed information on dosage and timing of exposure. No minimum exposure
parameters were set for selection; thus, these represent the normal range of dosages and durations commonly used in treatment
of at-risk pregnancy in Denmark during this period. Exposures
did not differ by sex. Timing of exposure occurred during periodsassociated with sexual differentiation of the CNS in humans.
123
Measures
Interview Data
Information on sexual orientation was obtained as part of a
structured interview conducted by a psychologist at the Institute
for Preventive Medicine in Copenhagen, Denmark. Psychologists were blind to the exposure status of all subjects. The following sexual orientation variables were addressed in the
comprehensive interview and coded as follows.
Same-Sex Variables
1. Self-labeled sexual orientation: (heterosexual/non-heterosexual) [This item was drawn from a question asking participants whether they considered themselves to be heterosexual,homosexual,bisexual,‘‘don’tknow.’’Giventhesmall
numbers in the non-heterosexual categories, the data were
recoded to heterosexual/non-heterosexual for analysis.]
Arch Sex Behav (2017) 46:1239–1249
1243
Table 2 Descriptive statistics for progesterone exposure variables
(n = 34)
Progesterone exposure variables
N
(%)
1st only
14
41.2
1st–2nd
12
35.3
2nd only
6
17.6
2nd–3rd
2
5.9
3rd only
0
0.0
Total dosage (mg)
40–300
11
32.4
301–999
14
41.2
1000–1999
5
14.7
2000–5400
4
11.8
8–29
9
26.5
30–60
12
35.3
61–120
8
23.5
121–158
5
14.7
Timing of exposure (trimesters)
Duration of exposure (days)
Average daily dosage (mg/day)
3–9
16
47.1
10–25
7
20.6
26–50
11
32.4
2. Lifetime attraction to own sex: (yes/no)
3. Current attraction to own or both sexes: (yes/no)
4. Kissed own sex: (yes/no)
5. Having been partially undressed in a sexual situation with
own sex: (yes/no)
6. Having been fully undressed in a sexual situation with own
sex: (yes/no)
7. ‘‘Intercourse’’with own sex: (yes/no) [Our interview data
indicated that women generally interpreted this question
to mean mutual genital sexual stimulation; men usually
interpreted this as anal intercourse.]
Other-Sex Variables
8. Having kissed other (‘‘opposite’’) sex: (yes/no and age at
first engagement)
9. Having been partially undressed in a sexual situation with
other sex: (yes/no and age at first engagement)
10. Having been fully undressed in a sexual situation with
other sex: (yes/no and age at first engagement)
11. Intercourse with other sex: (yes/no, and age at first engagement).
Items 4–11 were coded from questions asking age at first participation in each behavior, an approach developed by Kinsey (Kinsey et al., 1948; Kinsey, Pomeroy, Martin, & Gebhard,
1953). Asking age at first engagement signals participants that
one is non-judgmental about their engagement in particular
sexual behaviors. A postpubertal criterion was applied for age at
first engagement in these behaviors. Specifically, age at puberty
(whichwasassessed by aseparate set ofquestionsaboutmarkers
ofpuberty)wascomparedtothereportedageat first engagement
in the behaviors. The very few reports of behaviors prior to
puberty were not included in these analyses as they could have
been childhood sexual exploration. This criterion was consistently applied across all subjects and for both same-sex and
other-sex behaviors. The number of participants engaged in the
same-sex behaviors was insufficient to conduct a statistical analysis of age for thosevariables. However, we wereable to analyze
age at first engagement in the heterosexual behaviors.
Questionnaire Data
Sexual Behavior Inventory (SBI) This self-administered
questionnaire was created for the PDP (Reinisch et al., 1993)
to assess whether or not 67 different sexual behaviors have
been tried. Three items on the questionnaire were relevant to
sexual orientation: (1) to ‘‘go to bed with’’ a person of your
own sex (in Danish, this item is understood to mean intercourse or mutual genital contact); (2) to masturbate in the
presence of another person(s) of the same sex; and (3) to
masturbate in the presence of another person(s) of the opposite sex.
Sexual Attitudes Questionnaire (SAQ) This self-administered
questionnaire, created for the PDP (Reinisch et al., 1993),
includes 120 items from the original Eysenck Inventory of
Attitudes toward Sex (Eysenck, 1976). Participants indicated
their agreement/disagreement on a three-point scale (yes, ?,
no; scored 2, 1, 0, respectively) with 179 statements about
various aspects of sexuality. There are two factors relevant to
sexual orientation: attraction to males and attraction to females.
Each factor has six items and shows good internal consistency
(Cronbach’s alphas .88 for attraction to males and .90 for attraction to females). Items for attraction to males and attraction to
females were worded identically except for the sex of the object
of attraction. Questions (in Danish) were scattered throughout
the SAQ. The 12 questions about attraction to males/females
translated into English are as follows:
• IusuallytakealonglookwhenImeetanattractiveman/woman
in the street.
• Male/female sexual organs are attractive.
• I often have fantasies about male/female sex partners.
• Now and then I think about sex when I am in an attractive
man’s/woman’s company.
• I sometimes have fantasies about being with two or more
men/women at the same time.
• I regularly meet men/women whom I find attractive.
123
1244
Procedure
Thestudy was approved bytheappropriatereview boardsforthe
protection of human subjects in both the U.S. and Denmark. The
data presented in this article assessing sexual orientation represent a subset of a large evaluation battery (Reinisch et al.,
1993). The purpose and procedures for the study were explained
to participants, and informed consent was obtained. A psychologist supervised the collection of questionnaire data and conducted the interview during a full day of evaluation at the Institute for Preventive Medicine. Evaluators and participants were
blind regarding treatment status.
Data Analysis
We hypothesized that same-sex behavior and attraction would
be higher for the exposed compared to the unexposed participants. Data were first examined for interactions between sex of
participant and exposure to lutocyclin. Finding none, data from
men and women were then combined for statistical analysis of
exposure effects, with the exception of scores for attraction to
males and attraction to females as these are more easily understood when presented separately by sex. For dichotomous variables, Tango’s (1998) test of the differences in proportions in
matched pairs was used. Unlike the McNemar test, Tango’s test
accommodates 2 9 2 tables with off-diagonal zero cells. For continuous variables, paired t tests were performed to compare data
from exposed and unexposed participants. Spearman’s rho was
used to evaluate the correlation between attraction to males and
attraction to females. Relationships between progesterone treatment parameters and outcomes of interest were assessed by the
Kolmogorov–Smirnov Z test of equality of distributions. We
report p values for two-tailed tests, a conservative criterion
given our directional hypotheses which would justify use of
one-tailed tests.
Results
As shown in Table 3, compared to their matched controls,
exposed cases showed a consistent pattern of higher percentages
of:
1. Self-labeled identification as other than heterosexual (i.e.,
homosexual, bisexual, or‘‘don’t know’’) (20.6% exposed,
0% controls, p.01). Among the exposed men, one identified as homosexual, two as bisexual, and two said‘‘don’t
know.’’ Among exposed women, two identified as bisexual. All other subjects, exposed and unexposed, self-identified as heterosexual;
2. ‘‘Ever Attracted to Own Sex’’ (29.4% exposed, 5.9%
controls, p = .02);
123
Arch Sex Behav (2017) 46:1239–1249
3. ‘‘Currently Attracted to Own or Both Sexes’’ (17.6% exposed, 2.9% controls, p.06); and
4. Various sexual behaviors with their own sex including
‘‘kissed own sex’’; partially and fully undressed in a sexual
situation; ‘‘intercourse’’; ‘‘gone to bed’’; and ‘‘masturbated
together’’ (range 14.7–24.2% exposed cases, 0–9.1% of
controls). In general, behavioral patterns were consistent for
individuals. For example, all those reporting ‘‘intercourse’’
with a person of the same sex also reported ‘‘going to bed’’
with; being fully and partly undressed in a sexual situation
with; and kissing someone of the same sex.
None of those who identified as other than heterosexual had
own sex attractions or engaged in these same-sex behaviors
were concordant with their matches.
Exposure status was not associated with heterosexual experience—all participants reported sexual behavior with the other
sex. The small number of cases who engaged in same-sex sexual
behaviors precluded statistical analyses of‘‘Age at First Engagement’’ in those behaviors, but this measure for heterosexual
behaviorsdidnotdifferaccordingtoexposurestatus(seeTable 4).
For men, scores on the attraction to males scale were significantly higher for exposed cases compared to controls, paired
t(16) = 2.76, p.02, two-tailed, but scores did not differ for the
attraction to females scale (see Table 5). For women, scores on
attraction to females scale were not different between exposed
and unexposed cases, but there was a statistical trend toward
higher scores on the attraction to males scale for exposed
women, paired t(16) = 1.92, p = .07, two-tailed. Thus, exposure
was positively associated with higher scores on the attraction to
males scale regardless of sex, total group of males, and females
combined paired t(33) = 3.31, p.01, two-tailed. Although a
bipolar model of sexual orientation (Kinsey et al., 1948; Sanders
et al., 1990) would predict a strong negative relationship between
scale scores for attraction to males and attraction to females, this
was not the case (for men, Spearman’s rho = -.10; for women,
rho = .23; both ns).
In light of findings linking birth order and number of older
brothers to homosexual orientation among men (Blanchard &
Bogaert, 1996; Cantor, Blanchard, Paterson, & Bogaert, 2002),
this possible confound was examined. Neither birth order nor a
number of older brothers confound the current findings. Not
surprising given the matching, birth order did not differ between
exposed and unexposed men (M = 1.76, SD = .96) and the
numberwhohadolderbrotherswasthesamefortheexposedand
unexposed groups (n = 5 for each group).
A systematic investigation of the relationship between progesterone treatment parameters (i.e., total dosage, average daily
dosage, timing, and duration of progesterone exposure) and outcomes of interest was precluded by the high variability in maternal medical treatment and the intercorrelations among the various treatment parameters. Nonetheless, it is noteworthy that the
seven individuals who self-identified as other than heterosexual
Arch Sex Behav (2017) 46:1239–1249
1245
Table 3 Comparison of sexual orientation, attraction, and behavior variables for prenatally progesterone-exposed (Exp) and unexposed (Un)
participants
Men
(17 pairs)
Women
(17 pairs)
Total group
(34 pairs)
Exp
Un
Exp
Un
Exp
n
n
n
n
n
z Statistica p (two-tailed)b
Un
(%)
n
(%)
Same sex
Non-heterosexual self-labeled identityc,d,e
Ever attracted to own sex
c
5
0
2
0
7 20.6
0 0
2.56
.008
6
0
4
2
10 29.4
2 5.9
2.31
.021
Current attraction to own or both sexesc,e
3
0
3
1
6 17.6
1 2.9
1.88
.059b
Kissed own sexc,e
3
0
4
1
7 20.6
1 2.9
2.12
.034
Has been partially undressed in a sexual situation with own sexc,e,f
3
0
4
1
7 20.6
1 2.9
2.12
.034
Has been fully undressed in a sexual situation with own sexc,e,f
2
0
4
1
6 17.6
1 2.9
1.88
.059b
‘‘Intercourse’’with own sexc,e,f
2
0
3
0
5 14.7
0 0
2.23
.025
‘‘Gone to bed’’with person of own sexe,f,g
2
0
4
1
6 17.6
1 2.9
1.89
.059b
g
6
2
2
1
8 24.2
3 9.1
1.67
.095b
Kissed other sexc
17
17
17
17
34 100
34 100
na
na
Has been partially undressed in a sexual situation with other sexc
17
17
17
17
34 100
34 100
na
na
34 100
na
na
Masturbated in the presence of same sex
Other (‘‘opposite’’) sex
Has been fully undressed in a sexual situation with other sex
c
17
17
17
17
34 100
Intercourse with other sexc,h
16
17
17
17
33 97.1 34 100
1.00
ns
Masturbated in the presence of other sexg
6
8
4
6
10 30.3 14 42.4 1.15
ns
a
Tango’s (1998) test of the differences in proportions in the pair-sample design was used (na = Not applicable)
b
We have used a conservative criterion for statistical significance. The hypotheses are directional, and therefore, one-tailed tests may be justified. If
one-tailed tests are used, all same-sex variables in this table would be significant at p.05 (na = Not applicable)
c
From the interview
d
Self-identification as lesbian, homosexual, bisexual, or‘‘don’t know’’was recoded as non-heterosexual. Specifically, among the exposed men one
identified as homosexual, two as bisexual, and two said‘‘don’t know.’’Among exposed women, two identified as bisexual. All other subjects, exposed
and unexposed, self-identified as heterosexual
e
None of those who identified as other than heterosexual; had own sex attractions; or engaged in these same-sex behaviors, were concordant with their
matches
f
In general, behavioral patterns were consistent for individuals. For example, all those reporting ‘‘intercourse’’ with a person of the same sex, also
reported ‘‘going to bed’’with, being fully and partly undressed in a sexual situation with, and kissing someone of the same sex
g
From the Sexual Behavior Inventory
h
Only one participant, a l
