Prenatal hormones have been proposed as key factors impacting child development as well as long-term health and disease. Digit ratio (the ratio of the lengths of the second to fourth digits; 2D:4D) has been proposed as a sexually dimorphic, noninvasive marker of prenatal androgen exposure that can be reliably measured in children and adults. To date, few longitudinal pregnancy cohort studies have examined childhood digit ratio in relation to other relevant measures including prenatal hormones and androgen-sensitive outcomes. To augment the current literature on this topic, we measured right-hand digit ratio in 4-year-old children participating in The Infant Development and the Environment Study, a multicenter longitudinal cohort study that has been following mother–child dyads since the first trimester of pregnancy (n = 321). We assessed sex differences in digit ratio and fit multivariable linear regression models to examine digit ratio in relation to: (1) child sex; (2) maternal sex steroid hormone concentrations in early pregnancy; (3) newborn anogenital distance, another proposed measure of sensitivity to prenatal androgens; and (4) gender-typical play behavior as measured by the Preschool Activities Inventory (PSAI) at age 4. We observed no sex difference in digit ratio; the mean 2D:4D was 0.97 ± 0.05 mm in both sexes. Furthermore, digit ratio was not associated with maternal sex steroid concentrations in early pregnancy, anogenital distance in either sex, or PSAI scores in either sex in covariate-adjusted models. In conclusion, we observed no evidence that early childhood digit ratio was associated with child sex or hormone-sensitive measures in this cohort.

The critical period during which maternal hyperglycemia predisposes offspring to develop reproductive disorders in adult life is not known. The relationship between maternal hyperglycemia at different stages and reproductive functions of male offspring was investigated. A single intraperitoneal injection of alloxan (90 mg/kg body weight) was administered at gestation days (GD) 1, 8 and 15. Animals were subsequently given 10% glucose solution daily as drinking water until parturition. All male pups were sacrificed on the 63rd day of postnatal life. Birth weight, anogenital distance index (AGDi), testes descent day, preputial separation day, sperm profile, serum testosterone, luteinizing hormone and follicle-stimulating hormone levels and the histology of the testis were assessed. Data significance test was based on 95% confidence interval. GD1 pups showed a significant increase in mean birth weight, whereas GD8 pups and GD15 pups had significantly reduced birth weight as compared with control. AGDi was significantly increased in GD8 and GD15 pups. Testes descent and preputial separation in all the experimental groups were significantly earlier. There was a significant reduction in sperm count and viability in GD8 offspring. Sperm motility was reduced in all test groups. Testosterone level was reduced in all test groups. Histology of the testis showed varying degrees of pathologies. It was deduced from this study that maternal hyperglycemia caused alterations in reproductive functions in male offspring of Wistar rats irrespective of the period of gestation involved, although GD8 pups were most severely affected.

Fetal programming hypothesis presupposes that stimulus or insult acting during critical periods of uterine growth and development may permanently alter tissue structure and function. Ricinus communis oil (RCO) has been reported to possess/used as laxative, labor-inducing and estrogenic properties. Generational reproductive effects of maternal exposure to RCO was investigated in rats. A total of 25 pregnant rats randomly assigned to five equal groups were treated with distilled water (control, group 1), RCO (950 mg/kg p.o.) during gestation days (GD) 1–7, 7–14, 14–21 and 1–21, respectively. Birth weight, morphometric data, anogenital distance (AGD), pubertal age, sperm parameters, hormonal profile, organ weight and histopathology were determined in the first (F1) and second (F2) filial generations. Results showed a significant decrease (P<0.05) in birth weight/morphometric data in male pups from the GD 1–7 and 7–14 groups. AGD decreased significantly in RCO-treated F1 males. Pubertal age of F1 females decreased significantly (P<0.05) compared with controls. At postnatal day 90, F1 males from the RCO-treated group showed significant decrease in testis weight, body weight, sperm count, motility and normal morphology. Testosterone levels were significantly decreased in RCO-treated F1 males, which also showed testicular interstitial edema and epididymal hypospermia. Only pubertal indexes were altered in F2 rats. Maternal exposure to RCO at early gestation periods impaired androgen-mediated reproductive end points in the first generation of rats. RCO exhibits endocrine disrupting capabilities.

The prenatal hormonal milieu is widely believed to shape health later in life; however, there are considerable methodological challenges associated with measuring the in utero hormonal environment. Two potential biomarkers of prenatal androgen exposure that can be measured postnatally have been proposed: anogenital distance (AGD) and the ratio of the second to fourth digits of the hand (2D:4D). Although both measures are widely used research tools, their use in adult women may be complicated by the dramatic fluctuations in reproductive hormones across the menstrual cycle. To determine whether there is cyclical variation in these biomarkers, we conducted a longitudinal study of 12 naturally cycling, nulliparous adult women. Trained examiners assessed two measures of AGD [anus to clitoris (AGD-AC) and anus to fourchette (AGD-AF)] and 2D:4D in both hands for the duration of three menstrual cycles, taking measurements during the follicular, peri-ovulatory and luteal phases of each cycle. Despite the small sample size, longer (more masculine) AGD was associated with lower (more masculine) digit ratios, as predicted by the literature. Using multi-level linear regression models, we found that AGD and 2D:4D measurements did not differ significantly across cycle phases. AGD-AF and digit ratios in both hands were associated with age at menarche, suggesting a possible common developmental trajectory. These results demonstrate that AGD and 2D:4D are stable across the menstrual cycle. In addition, research is needed to determine how reliably these measures reflect the in utero hormonal milieu.

Reproductive effects from phthalate exposure have been documented mostly in animal studies. This study explored the association between prenatal exposure to phthalate metabolites, anogenital distance and penile measurements in male newborns in Toluca, State of Mexico. A total of 174 pregnant women provided urine samples for phthalate analysis during their last prenatal visit, and the 73 who gave birth to male infants were included in the study. The 73 male newborns were weighed and measured using standardized methods after delivery. After adjusting for creatinine and supine length at birth, significant inverse associations were observed between an index of prenatal exposure to total phthalate exposure and the distance from the anus to anterior base of the penis (β = −0.191 mm per 1 μg/l, P = 0.037), penile width (β = −0.0414, P = 0.050) and stretched length (β = −0.2137, P = 0.034); prenatal exposure to mono-2-ethylhexyl phthalate exposure was associated with a reduction in the stretched length of the penis (β = −0.2604, P = 0.050). Human exposure to phthalates is a public health concern, and the system most vulnerable to its potential effects seems to be the immature male reproductive tract.