It is uncommon wisdom but taking good care of your thyroid in early pregnancy can help you to have a natural birth and avoid having a cesarian due to breech presentation. Research chows that when your thyroid hormones are low at the end of the first trimester you are more likely to have a breech birth which usually necessitates a cesarian section. Having a TSH higher than 2.5 or free thyroxine (T4) in the lowest tenth percentile of the reference range is proven to increase the risk that you baby will not turn head-down and instead may have to be born with cesarian delivery.
Most physicians will not test your thyroid during pregnancy so it is wise to ask for testing upon confirmation of pregnancy and at the end of the first and second trimester to keep your thyroid hormones stellar.
A 2004 study (1) from the Netherlands - published in BJOG - evaluated the relation between breech position at term and low/normal free T4 levels in mothers who were not experiencing overt thyroid disease.
Thyroid hormone values were assessed at twelve weeks of pregnancy in a large group of 204 women, they were divided into two groups: those with low free T4 levels - below the lower tenth percentile of the reference range - and those with healthy free T4 levels between the middle of the range and the top 90th percentile. Thyroid function was re-checked at 24 and 32 weeks.
Breech presentation at term (37 weeks) was closely tied to low free T4 levels at 12 weeks indicating that having stellar thyroid hormones in early pregnancy has a protective effect upon delivery. The researchers concluded that:
"Women with hypothyroxinaemia (fT4 level at the lowest 10th centile) during early gestation but without overt thyroid function are at risk for fetal breech presentation at term (>37 weeks of gestation)."
This study is important because it highlights the fact that free T4 levels in early pregnancy, not TSH is a risk for Breech presentation; it is important to test both the TSH and free T4 in pregnancy. Having free T4 levels in the lowest tenth percentile of the range is called 'hypothyroxinemia.' Aside from increasing the rate of breech presentation a child’s IQ can also be lowered and developmental delays are more common especially speech and hearing delays.
Another similar study (2) also examined the relationship between low thyroid function during pregnancy and breech presentation at term. One thousand and fifty eight pregnant women were observed from twelve weeks of pregnancy to term and thyroid hormone values were monitored at 12, 24 and 36 weeks of pregnancy.
The women with breech presentation at the end of pregnancy were far more likely to have a higher TSH at this time.The incidence of breech presentation was more than doubled (11% compared to 4.8%) in women with a TSH equal to or above 2.5 mIU/l at 36 weeks. The study also found that:
“Women with TSH below the 5th percentile had no breech presentations.”
It may be that having a low TSH is protective against breech birth; the study concluded that:
"Women with TSH levels above 2.5 mIU/l during end gestation are at risk for breech presentation, and as such for obstetric complications."
Another study from the Netherlands (3) followed one hundred and forty one women with breech presentation at the end of their pregnancies as they underwent 'external cephalic version' (ECV) a technique used to turn a breech baby prior to birth and tested their thyroid hormones. The study showed that women with higher TSH levels indicating poor thyroid function were less likely to have a successful ECV result necessitating cesarian birth. The study concluded that;
"Higher TSH levels increase the risk of ECV (external cephalic version) failure."
Hopefully this information will inspire you to ask your physician to test your thyroid function with a TSH and free T4 test upon confirmation of pregnancy and at the beginning of the second and third trimesters. Ideally the TSH should be below 2.5 mIU/l and the free T4 in the top third of the reference range.
1. BJOG. 2004 Sep;111(9):925-30. Low concentrations of maternal thyroxin during early gestation: a risk factor of breech presentation? Pop VJ, et al.,
2. Clin Endocrinol (Oxf). 2010 Jun;72(6):820-4. Epub 2009 Oct 15. Maternal thyroid function during gestation is related to breech presentation at term. Kuppens SM, et al.,
3. BMC Pregnancy Childbirth. 2011 Jan 26;11:10. Maternal thyroid function and the outcome of external cephalic version: a prospective cohort study. Kuppens SM, et al.,