Increased maternal TSH and decreased maternal FT4 are associated with a higher operative delivery rate in low-risk pregnancies: A prospective cohort study

Abstract

BackgroundThe increasing number of operative deliveries is a topic of major concern in modern obstetrics. Maternal thyroid function is of known influence on many obstetric parameters. Our objective was to investigate a possible relation between maternal thyroid function, and operative deliveries. Secondary aim was to explore whether thyroid function was related to specific reasons for operative deliveries.MethodsIn this prospective cohort study, low-risk Caucasian women, pregnant of a single cephalic fetus were included. Women with known auto-immune disease, a pre-labour Caesarean section, induction of labour, breech presentation or preterm delivery were excluded. In all trimesters of pregnancy the thyroid function was assessed. Differences in mean TSH and FT4 were assessed using t-test. Mean TSH and FT4 levels for operative deliveries were determined by one way ANOVA. Repeated measurement analyses were performed (ANOVA), adjusting for BMI, partiy, maternal age and gestational age at delivery.ResultsIn total 872 women were included, of which 699 (80.2 %) had a spontaneous delivery. At 36 weeks gestation women who had an operative delivery had a significantly higher mean TSH (1.63mIU/L versus 1.46mIU/L, p = 0.025) and lower mean FT4 (12.9pmol/L versus 13.3pmol/L, p = 0.007)) compared to women who had a spontaneous delivery. Mean TSH was significantly higher (p = 0.026) and mean FT4 significantly lower (p = 0.030) throughout pregnancy for women with an operative delivery due to failure to progress in second stage of labour, compared to women with a spontaneous delivery or operative delivery for other reasons.ConclusionsIncreased TSH and decreased FT4 seem to be associated with more operative vaginal deliveries and Caesarean sections. After adjusting for several confounders the association remained for operative deliveries due to failure to progress in second stage of labour, possibly to be explained by less efficient uterine action.

Preconception TSH and pregnancy outcomes: a population‐based cohort study in 184 611 women

“…Further research is warranted in this field. Other adverse events were also reported in hypothyroid mothers, such as pre‐eclampsia, gestational diabetes, premature rupture of membranes, CS, as well as lower Apgar score and cognitive developmental delay in their offspring …”

Women with Subclinical Hypothyroidism Are at Low Risk of Poor Pregnancy Outcome in Japan

“…Increased operative deliveries including cesarean section were reported in low-risk pregnancies with increased TSH and decreased free T4, and a less efficient uterine contraction was thought to be a cause of the failure to progress to a normal delivery (Monen et al 2015). In the current study, 6 of 13 emergency cesarean sections were the result of maternal indication in the eTSH group.…”

The impact of levothyroxine exposure on delivery outcome in hypothyroid pregnant women (PETAL study): A five-year retrospective cohort study

“…1,2 Some studies have also demonstrated a possible association with dystocia and fetal malpresentation leading to caesarean deliveries (CD), and this was explained by the possible thyroid hormonal influence over myometrial cell contraction and relaxation. 3,4 Turunen et al supported this finding while observing an increased CD rate for hypothyroid pregnant women (21.2%) compared to euthyroid pregnant women (15.7%). 5 They also observed a persistent significant risk association between CD and hypothyroidism treated with levothyroxine (OR 1.1, 95% CI 1.1-1.2) compared to euthyroidism.…”