According to the findings of a Dutch study, published in Clinical Endocrinology, low levels of the 'thyroxine' hormone, which is already known to set hurdles for expectant mothers by increasing the risk of miscarriage, premature birth and pre-eclampsia, is also apparently increases the chances of strenuous labor during delivery.

Noting that "low to normal" levels of thyroxine - a hormone produced by thyroid gland - can be problematic, the Dutch team of researchers discovered that pregnant women with insufficient thyroxine levels are more likely to have longer and more difficult labor, because their babies are, more often than not, positioned wrongly.

The study, involving 1000 healthy expectant mothers, found that those women who had lower thyroxine levels at 36 weeks of pregnancy often had the baby's head positioned abnormally, and ran the risk of an assisted delivery with forceps, ventouse or a Caesarean.

Noting that the babies in such cases are stuck in an 'awkward' way and fail to get into the optimal position for labor, lead researcher Professor Victor Pop opined that the relative lack of hormone apparently also hampers the unborn baby's movements.

Pop further told BBC News: "Recent findings have shown that motor development in children at the age of two is related to low levels of thyroid hormone in pregnancy. It follows that impaired maternal thyroid function could also influence foetal movement."