Childbearing people are advised to take a variety of precautions and avoidances during pregnancy. They include not smoking or drinking alcohol, and taking prenatal vitamins and supplements daily. Sticking to a doctor's advice helps ensure a baby's health during and after its time in the womb.
The results of a new study suggest a pregnant person's diet may have even more of an effect than previously thought on the health of a developing fetus. As a consequence of these findings, individuals who are currently pregnant may receive updated advice from their health care professionals.
Xenoestrogens pass the placental barrier
The placental barrier offers an unborn child some protection from specific environmental toxins, drugs and bacteria. This new research, based at the University of Vienna, focused on xenoestrogens - chemical compounds primarily found in food that can substantially affect the body's hormonal balance.
Scientists wanted to see what happened to xenoestrogens in the body, and specifically, whether they could reach a growing fetus. While using technology to track their movement within the body, researchers realized xenoestrogens could get through the placental barrier.
More specifically, the scientists looked at a type of xenoestrogen called zearalenone, a food estrogen produced by fungi and found in bread and other grain-based products. This is the first time research has proved that zearalenone, a mycotoxin, could get through the placental barrier.
How did scientists reach this conclusion?
The team used fully functional placentas donated after planned cesarean sections. Acquiring human placentas was important for reliably tracking how zearalenone travels through the body and is metabolized as there are species-specific differences in the placenta's structure, as shown in a 2016 paper in Annales d’ Endocrinologie that looked at mammalian placentas.
The scientists measured zearalenone levels in the placenta tissue and used the ex vivo perfusion model to examine the metabolic processes of enzymes inside the placenta. Perfusion occurs when blood flows or is pumped through an organ. During this research, the scientists used a machine to send blood through the placentas which negated the need to preserve them with ice.
They checked the amount of zearalenone in a nutrient solution before and after it entered the placenta. More specifically, the scientists checked the amount of zearalenone in the maternal and fetal circulation at the end of perfusion, the amount in the fetal tissue following the end of perfusion and the amount present in collected samples during perfusion. The team used data analysis software to track the amount of zearalenone added to the maternal circulation when perfusion began.
These results complemented earlier findings by some members of this University of Vienna team, where an analytical process enabled the measurement of 50 xenoestrogens at once in less than a half-hour. It used a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to measure the concentrations of multiple classes of estrogens in human urine, breast milk and serum.
In a University of Vienna press release, Tina Bürki, a researcher on the project, explained, “If we ingest environmental contaminants, they may be detoxified in the body via our metabolism and then excreted. However, some enzymes make these substances even more bioactive." The scientists concluded that the placenta makes metabolic products that are about 70 times more estrogenic than zearalenone. This means that even a small concentration of zearalenone could have a more significant impact on the fetus than previously thought.
Stricter dietary monitoring may be necessary
In their published research paper, the University of Vienna scientists stated that women with unbalanced diets could expose their fetuses to higher levels of zearalenone. They recommend that pregnant individuals undergo biomonitoring to check for toxic levels.
In 2011, Italian researchers published data showing that more than 25% of baby formulas tested contained zearalenone and derivative substances. At that time, the researchers proposed closer scrutiny of baby foods and their ingredients. The results may influence how pediatricians provide nutritional coaching to new parents who need to choose the safest infant formulas. The later study from the University of Vienna indicates pregnant women should start to make dietary changes too.
Keeping zearalenone out of a pregnancy diet is not only helpful for humans aiming to have healthy babies. A 2017 study linked zearalenone exposure in pregnant rats to lower birth rates and less viability for the newborn offspring. It could even make a rat's progeny less able to reproduce later.
Environmental toxins pose risks too
Besides the foods people eat while pregnant, more threats in the environment could harm a fetus. As such, individuals preparing for childbirth may need to be exceptionally careful about their exposure to toxins beyond things ingested in their diet.
For example, research has highlighted that inhaled black soot particles can make their way through the circulatory system and eventually to a developing baby. This could be problematic for individuals living in highly polluted cities or those who have jobs that regularly expose them to elevated levels of pollution.
Similarly, a scientific investigation revealed that air pollution increases the risk of Chinese women experiencing miscarriages without noticeable symptoms. The research involved multiple universities and tracked more than 250,000 pregnant women in Beijing across eight years. Nearly 17,500 of them went through these so-called missed miscarriages.
Toxicity can be a factor in the products people purchase, too. The Endocrine Society published material showing that bisphenol A (BPA), a common component of plastic water bottles, can alter a child's brain development later in life if a pregnant woman uses items that have BPA in them.
More research required
Expectant parents often feel nervousness accompanying their excitement about welcoming a new family member. Feeling that unease is understandable. Nevertheless, health care professionals can equip parents-to-be for what’s ahead by urging them to exercise caution concerning the matters above and other relevant issues or risks.
Further evaluations are needed before scientists can reach definitive conclusions about what zearalenone does to fetuses in the long-term. For now, experts in the scientific community believe some of the best ways to avoid potentially negative consequences are to maintain balanced diets during pregnancy and try to prevent heightened exposure to known hazardous contaminants in the environment.