Parental height differences predict the need for an emergency caesarean section

Abstract

More than 30% of all pregnancies in the UK require some form of assistance at delivery, with one of the more severe forms of assistance being an emergency Caesarean section (ECS). Previously it has been shown that the likelihood of a delivery via ECS is positively associated with the birth weight and size of the newborn and negatively with maternal height. Paternal height affects skeletal growth and mass of the fetus, and thus might also affect pregnancy outcomes. We hypothesized that the effect of newborn birth weight on the risk of ECS would decrease with increasing maternal height. Similarly, we predicted that there would be an increase in ECS risk as a function of paternal height, but that this effect would be relative to maternal height (i.e., parental height differences). We used data from the Millennium Cohort Study: a large-scale survey (N = 18,819 births) with data on babies born and their parents from the United Kingdom surveyed 9 to 12-months after birth. We found that in primiparous women, both maternal height and parental height differences interacted with birth weight and predicted the likelihood of an ECS. When carrying a heavy newborn, the risk of ECS was more than doubled for short women (46.3%) compared to tall women (21.7%), in agreement with earlier findings. For women of average height carrying a heavy newborn while having a relatively short compared to tall partner reduced the risk by 6.7%. In conclusion, the size of the baby, the height of the mother and parental height differences affect the likelihood of an ECS in primiparous women.

Figure 1. The effect of birth weight (means and 95% confidence intervals of raw data) on the risk of ECS.

Birth weight in bins of 0.5 kg and bins lower than 2.5 and higher than 4.5 kg were pooled. The confidence interval was determined using the Agresti-Coull method .

Figure 2. The effect of maternal height, parental height differences and birth weight on ECS risk.

The effects (means and 95% confidence interval of raw data) are shown for (a) maternal height, (b) maternal height and birth weight (c) parental height differences and (d) parental height differences and birth weight. Height is divided into bins of 5 cm (bins lower than 145 for maternal height and −5 cm for parental height differences and higher than 180 and 35 cm were pooled) and birth weight was divided into tertiles. The confidence interval was determined using the Agresti-Coull method .