07 Mar Can Phthalates Alter Sex Development During Pregnancy?
MedicalResearch.com Interview with:
Dr. Jennifer Adibi, MPH ScD
University of Pittsburgh, Public Health
Assistant Professor, Epidemiology
Assistant Professor, Department of Obstetrics/Gynecology and Reproductive Sciences
Affiliate, Dept. of ObGYN and Reproductive Sciences
University of California, San Francisco
Medical Research: What is the background for this study?
Dr. Adibi: Prenatal exposure to phthalates in rodents can cause defects in male sexual development including a shorter distance between the anus and the genitalia (anogenital distance or AGD). Human studies have shown a correlation between higher prenatal phthalate urinary concentrations in the mother and shorter AGD in males. AGD in males is related to fertility and reproductive health over the lifetime. In females, AGD was associated with numbers of ovarian follicles. The role of the placenta has not been considered in these studies. A placental hormone called human chorionic gonadotropin (hCG) is essential for normal male development. Our previous research has shown that hCG expression by human placental cells is disrupted by phthalate concentrations equal to what we measured in maternal urine. The placenta secretes molecules early in pregnancy that might provide an opportunity to detect these effects in humans.
Medical Research: What are the main findings?
Dr. Adibi: In 350 pregnancies, we measured a significant association of maternal urinary concentrations of mono-n-butyl phthalate (MnBP) and monobenzyl phthalate (MBzP) with hCG in maternal blood in the first trimester. Higher phthalate concentrations were associated with higher hCG if the mother was carrying a female fetus, and lower concentrations if she was carrying a male fetus. In a high/low MnBP comparison, hCG was 15-fold higher in the higher exposed female fetuses. We also observed a relationship between maternal levels of hCG in the first trimester and anogenital distance in the newborns. The correlation was positive in female newborns, and inverse in male newborns. Similar to the parent study, we observed associations of higher first trimester MnBP and mono-2-ethyl hexyl phthalate (MEHP) with lower male anogenital distance. If we combined these findings into a mediation analysis, we estimated that approximately 20-30% of the phthalate-induced effect on anogenital distance was due to the phthalate disruption of hCG.
Medical Research: What should clinicians and patients take away from your report?
Dr. Adibi: With more studies and a better understanding of these relationships and the role of the placenta in endocrine disruption, we may have the possibility to detect these types of hormonal balances earlier in pregnancy and intervene within an early time frame to protect the long-term health of the future child. A pregnant woman should do her best to reduce her exposures; however, it is difficult to do this as intervention studies have shown. Meaningful changes in this exposure can only happen at the societal level with changes in regulation, industry practices, and innovation in consumer product design
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Adibi: We are going to repeat this study with serial maternal blood and urine samples before 14 weeks in pregnancy to better understand these relationships at the population level. First trimester hCG is widely available as it is measured as part of prenatal screening for Down’s Syndrome and other defects. These results support more studies to understand the role of placental hCG in fetal origins of health and disease, and as a target of endocrine disruption.
MedicalResearch.com Interview with: Dr. Jennifer Adibi, MPH ScD (2015). Can Phthalates Alter Sex Development During Pregnancy?