A baby whose mother was iron deficient before conception and during early pregnancy is at higher risk for profound and long-term negative effects on brain development, even if the deficiency didn’t reach anemia status, according to a University of Rochester Medical Center study.
An estimated 35 percent to 58 percent of all healthy women have some degree of iron deficiency. In fact, among women of childbearing age, one in five has the more serious iron-deficient anemia, according to the National Institutes of Health.
These findings are significant because many obstetricians overlook mild to moderate iron deficiency, and research authors believe that the results show the importance of monitoring a pregnant woman’s iron status beyond anemia.
Iron-deficient babies develop more slowly and display brain abnormalities, including slow language learning and behavioral problems. But until now, scientists were still unsure of the degree to which deficiency is linked to these problems, and at what time period during pregnancy the deficiency has the most impact on the central nervous system.
“What convinced us to conduct the present study were our preliminary data suggesting that cells involved in building the embryonic brain during the first trimester were most sensitive to low iron levels,” said Margot Mayer-Proschel, Ph.D., the lead researcher and an associate professor of biomedical genetics at URMC.
Using a highly controlled animal model system, researchers discovered that the critical period begins in the weeks just before conception and continues through the first trimester to the onset of the second trimester. Iron deficiency that begins in the third trimester was not associated with harm to the developing brain.
“This information is very important for clinical care,” said Monique Ho, M.D., assistant professor of obstetrics and gynecology and pediatrics at URMC.
“Prenatal care usually involves the recommendation of a multivitamin that contains iron, which is usually prescribed after pregnancy is confirmed or at the first prenatal visit. But not all women have access to prenatal care, and not all women can take the supplements in early pregnancy due to vomiting. This study suggests it might be prudent to begin routine monitoring to detect iron deficiency earlier.”
Through a diet study, the team observed the relationship between maternal iron intake and fetal iron levels and was able to pinpoint the critical periods of gestation when the developing baby’s central nervous system was most vulnerable. The researchers measured the resulting brain function using a common, non-invasive test called an auditory brainstem response analysis, or ABR.
The ABR testing, which detects the speed of information moving from the ear to the brain, was directed by co-author Anne Luebke, Ph.D. Researchers hoped to learn about impairments or changes in myelin, the insulating material that surrounds axons and is critical for normal brain function.
“In addition, ABR testing is routinely performed on human infants, and thus our study has an important component that can be translated to a clinical setting,” Luebke said.
The most surprising aspect, Mayer-Proschel said, was that the timing of the iron deficiency was far more significant than the degree of deficiency. This observation also seems to challenge the common theory that the placenta can minimize the impact of the mother’s deficiency on the baby.
“We refer to this as the window of vulnerability,” she said, “and it seems to be at a very early stage of development.” In previous studies, Mayer-Proschel discovered that iron-deficiency triggers an imbalance of neural precursor cells, which may be responsible for the abnormalities sometimes experienced by children up to two years of age.
“The next goals will be to better understand how maternal iron deficiency causes these changes in the offspring,” Mayer-Proschel said, “and most importantly, what are the opportunities for reversing the damage.”
The study is published in the scientific journal PLoS One.
Source: University of Rochester