BBC: Low [thyroid] hormone levels in pregnancy linked to hard birth

Expectant mums who are low in a hormone made by the thyroid gland in the neck are more likely to struggle in labour, findings suggest.

Not only are these labours generally longer and harder, they are also more likely to end in an assisted delivery with forceps, ventouse or a Caesarean.

The article talks about abnormal positioning of the infant prior to birth and information on problems for the infant during development, also, if the mother's thyroid hormones are off. 

To read the whole article: Low hormone levels in pregnancy linked to hard birth