Reproductive Lay Summaries

Phthalate exposure affects female reproductive development

Keywords: reproductive health, environmental exposures, phthalates, adolescent, puberty, endocrine disrupters

What is already known about this subject:

  • Certain environmental chemicals can affect reproductive health.
  • Phthalates are common in our environment and are found in industrial products, personal care products, plastics, paints and some pesticides. Phthalates can be absorbed via the skin, ingested or inhaled.
  • Phthalate exposure begins even before birth, and is continuous across the lifespan. Exposure to phthalates has been shown to interfere with male reproductive development, but it is not known if this is also the case in females.

What this Raine study adds:

  • Assessments of reproductive function in girls participating in the Raine study and phthalate levels in blood samples collected from their mothers during pregnancy revealed that phthalate exposure before birth had long term effects on reproductive development.
  • Phthalate exposure before birth was associated with long-term estrogenic effects on reproductive development, including increased uterine volume.
  • The effects of phthalates on reproductive development are an important consideration for reproductive health.

Hart, R., Doherty, D. A., Frederiksen, H., Keelan, J. A., Hickey, M., Sloboda, D., … Main, K. M. (2014). The influence of antenatal exposure to phthalates on subsequent female reproductive development in adolescence: a pilot study. Reproduction (Cambridge, England), 147(4), 379-90. doi:10.1530/REP-13-0331. [publink]

Estrogen levels vary widely in normal pregnancies and are affected by pregnancy-related factors

Keywords: hormones, child, perinatal characteristics, pregnancy

What is already known about this subject:

  • Exposure to high levels of estrogen before birth increases an individual’s risk of breast and prostate cancer.
  • Some pregnancy-related factors (twinning, preeclampsia, birth weight) may increase the risk of breast cancer by altering estrogen levels.
  • Understanding the relationships between estrogen exposure before birth and later health is difficult because ‘normal’ estrogen levels have not yet been established.

What this Raine study adds:

  • Estrogen levels in umbilical cord blood and pregnancy and birth-related data from Raine participants demonstrated that levels of umbilical cord estrogens do not differ between male and female infants, are reduced in twins, and are affected by labour and length of gestation.
  • There was a wide range of estrogen exposure in normal pregnancy.
  • Understanding normal estrogen exposure before birth will help in unravelling the relationship between estrogen exposure and the development of some cancers.

Hickey, M., Hart, R., & Keelan, J. A. (2014). The relationship between umbilical cord estrogens and perinatal characteristics. Cancer Epidemiology, Biomarkers & Prevention, 23(6), 946-52. doi:10.1158/1055-9965.EPI-13-1321.  [publink]

Increased risk of metabolic disease in adolescent girls with polycystic ovary syndrome

Keywords: adolescent, metabolic syndrome, overweight, polycystic ovary syndrome, risk factors

What is already known about this subject:

  • Polycystic ovary syndrome is the most common hormonal disorder in women of reproductive age. As well as being a leading cause of infertility, polycystic ovary syndrome is associated with metabolic disturbances that can lead to poor health.
  • Obesity is one of the main symptoms of polycystic ovary syndrome. Obesity also makes the symptoms of polycystic ovary syndrome worse, as fat stored around the stomach and waist is metabolically active and contributes to the existing metabolic disturbances.
  • Metabolic syndrome is a cluster of features related to cardiovascular disease, including obesity and increased blood pressure. Having polycystic ovary syndrome may predispose suffers to metabolic syndrome and long-term health problems. It is not known which features of polycystic ovary syndrome are the most important risk factors for metabolic syndrome.

What this Raine study adds:

  • Data from female Raine participants at 14 to 17 years of age (including height, weight, waist circumference, blood tests, metabolic tests, blood pressure and menstrual data) showed that one third of girls with polycystic ovary syndrome are also at risk of developing metabolic syndrome.
  • Overweight girls with polycystic ovary syndrome are at even greater risk of metabolic syndrome.
  • Medical or lifestyle interventions in overweight girls with polycystic ovary syndrome may help to protect their long-term health.

Hart, R., Doherty, D. A, Mori, T., Huang, R.-C., Norman, R. J., Franks, S., Sloboda, D., Beilin, L.,  Hickey, M. (2011). Extent of metabolic risk in adolescent girls with features of polycystic ovary syndrome. Fertility and Sterility, 95(7), 2347-53, 2353.e1. doi:10.1016/j.fertnstert.2011.03.001. [publink]