Diaper’s dirty little secret: Estrogen

EMORY / UNC-CHAPEL HILL (US) — Instead of blood or saliva samples, researchers now have a noninvasive way to measure an infant’s estrogen levels—data from dirty diapers.

Surprisingly little is known about hormone levels during infancy. By collecting fecal samples from cotton diapers, researchers can measure estradiol, a type of estrogen. The method is detailed in the current issue of Frontiers in Systems Biology.

“The development of an assay to measure estrogen from diapers might initially strike one as unnecessary or strange, but the need is real,” says Sara Berga, professor of gynecology and obstetrics at Emory University.

The well-documented role of estradiol in postnatal development of the body, brain, and behavior has in recent years raised specific concerns about how exogenous estrogens, or environmental estrogens—such as those found in soy, fruits, and vegetables, plastics, and common household items—affect lifelong health.

The method, previously used in nonhuman primates, will allow researchers to learn more about the association between estrogen levels in human infants and their long-term reproductive development as well as the development of sex-specific behaviors, such as toy preference or cognitive differences.

The method also will allow researchers to look at how early disruption of the endocrine system affects long-term maturation, a growing concern among researchers and physicians.

“The development of robust, noninvasive methods to measure these hormones in infants allows us to further investigate the association between postnatal hormone production and the development of sex-specific biology and behavior,” says senior author Michelle Lampl, professor of anthropology at Emory.

“We understand very little about the hormonal dynamics that occur during early development precisely because we lack a reliable way to track hormones in neonates and very young children. Having a way to track this critical hormone that influences behavior and the development of many important tissues, including the brain, will allow us to understand normal. This really is a great leap forward, and the investigators should be congratulated on this advance.”

Because of the ethical and practical difficulties of repeatedly taking blood samples from healthy infants, little data are currently available for charting the developmental pathways of estradiol. As such, existing data describe only the range of variability in hormonal levels—not developmental trends or what that variability might mean when it comes to individual physical and behavioral development.

The study included 32 infants. The infants’ parents retained soiled diapers after each diaper change during a 24-hour period. Bagged diapers were collected and then frozen and analyzed 24 hours to 12 months after collection.

Previous studies in primates have shown a close parallel between fecal levels of estradiol and serum values. Likewise, a comparison of fecal steroid levels between the study infants and previous studies of human adults shows an overlapping pattern, a pattern that is also seen in infant serum when compared with adult serum.

“These observations are the first report of human infant fecal estradiol levels and they provide a new tool for investigating early human development”, says Lampl. “Because infant diapers are plentiful, fecal samples can be collected frequently and over a long period of time. Future longitudinal studies will allow the association between fecal levels of steroids and physiological measures to be assessed, and expand our understanding independent of serum measures.”

The study was conducted by researchers at Emory, the University of North Carolina at Chapel Hill, and the University of Virginia Health System, Charlottesville.

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