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

L Monen,H Wijnen,Sg Oei,Vj Pop,Sm Kuppens,Th Hasaart

doi:10.1186/s12884-015-0702-1

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.

Highlights

The increasing number of operative deliveries is a topic of major concern in modern obstetrics
The reasons for Operative vaginal deliveries (OVD) and Caesarean Sections (CS) were classified as fetal distress, failure to progress in first stage of labour or failure to progress in second stage of labour
We found that women with an operative delivery for failure to progress in second stage of labour had higher mean Thyrotropine stimulating hormone (TSH) levels and lower mean Free thyroxine (FT4) levels throughout pregnancy, compared to women who delivered spontaneously or had an operative delivery for another reason

Summary

Introduction

The increasing number of operative deliveries is a topic of major concern in modern obstetrics. Our objective was to investigate a possible relation between maternal thyroid function, and operative deliveries. Increasing rates of Caesarean Sections (CS) is a topic of major concern in obstetrics. Both the incidences of planned and emergency CS are rising, without necessarily better neonatal outcomes [1, 2]. In previous studies it has been demonstrated that suboptimal maternal thyroid function (high maternal thyrotrophine stimulating hormone (TSH) and low free thyroxine (FT4)) is associated with adverse pregnancy outcomes [9,10,11,12]. Low FT4 has been associated with poor fetal neurodevelopment and psychomotor development in early childhood [13]

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