Does the anogenital distance change across pregnancy?

RESEARCH QUESTION

Does the length of the anogenital distance (AGD), an anthropometric biomarker of fetal androgen exposure, change across pregnancy? It has been suggested that AGD remains stable during adulthood with no changes across the menstrual cycle. No studies, however, have been carried out during pregnancy, during which women are exposed to important hormonal and anthropometric variations.

DESIGN

A cohort study of 186 singleton pregnant women recruited in the first trimester of pregnancy. Measurements from the anterior clitoral surface to the upper verge of the anus (AGD), and from the posterior fourchette to the upper verge of the anus (AGD) and body mass index (BMI) were obtained in each trimester. Generalized linear model for repeated measures was carried out to assess differences in AGDs and BMI across the three trimesters of the pregnancy.

RESULTS

In crude analyses, AGD was progressively and significantly longer as the pregnancy developed (first trimester: 87.69 ± 13.14mm; second trimester: 89.69 ± 13.47mm; third trimester: 91.95 ± 13.25 mm; P < 0.001), whereas AGD did not significantly change throughout pregnancy (first trimester: 28.37 ± 6.94 mm; second trimester: 28.09 ± 7.66 mm; third trimester: 28.94 ± 6.7 mm). In the multivariable mixed-effect models for fixed effect (trimester) and time-covariate (BMI), AGDs did not show significant associations with trimesters of pregnancy when BMI was included in the model.

CONCLUSIONS

Our results suggest that AGD and AGD, when adjusted by BMI, do not change throughout gestation despite maternal anthropometric variations during pregnancy. AGD may be a meaningful measurement at any time during pregnancy without considering BMI. Therefore, maternal AGD may be used as a prenatal biomarker of the mother's in-uteru hormonal exposure even during pregnancy.