Submitted by Shelby D Burns Wed 12/23/2009
Belly in print Findings published by the BBC this week tell us that expectant mothers who are low in a hormone made by the thyroid gland are more likely to struggle during labor. Too little of the hormone thyroxine is already known to complicate pregnancy, increasing the risk of miscarriage, premature birth and pre-eclampsia. A Dutch research teams now takes this a step further and says that even low to normal levels of thyroxine may cause problems, Clinical Endocrinology states. What they found was that babies are more often positioned poorly for delivery. Although the head may be down, the baby is facing the wrong direction putting pressure on the back and tailbone and often prolonging labor. Not only are these births longer and harder, they are also more likely to end with medical intervention via Caesarean section. The researchers from the University of Tilburg believe the hormone problem is common, perhaps effecting 10% of pregnancies, and that a blood test should become a routine part of prenatal care, presumably to identify and remedy the problem before the start of labor. In their study of nearly 1000 healthy pregnant women, lower levels of thyroxine at 36 weeks of pregnancy was strongly linked to abnormal positioning of the baby’s head and risk of assisted delivery. The theory put forward by the research team is that the relative lack of thyroxine might stop the unborn child from moving as it should. So instead of getting into the optimal position for labor, the baby is stuck facing the wrong direction. The team also pointed to recent findings which showed a link between low levels of thyroxine during pregnancy and motor development of two year olds. “It follows that impaired maternal thyroid function could also influence fetal movement,” said Professor Victor Pop who led the research team. During fetal development, all babies are unable to make their own thyroid hormones until 20 weeks into the pregnancy. Before that, the baby is entirely dependent on its mother for the hormone. There remains to be seen if there is a direct link between the two, what the team uncovered may not be causal. More work is needed to explain the connection. Nevertheless, the finding does underscore the importance of maternal health and perhaps the benefit of a thyroid hormone level check during pregnancy.