Advice for Pregnant Nurses
The nursing field is dominated by a female workforce, many of whom continue to work during pregnancy when they may be exposed to a number of nursing hazards. In this article we shall discuss shift work and its potential impact on pregnancy. In a separate article on diet we focus on the best foods to eat when pregnant. Several authors have cited work schedules as increasing risks to pregnant women and to foetal wellbeing. It has been suggested that maternal hormonal disturbance arising from sleep deprivation or circadian rhythm disruption might impair foetal growth or lead to complications of pregnancy.
For nurses, rotating shifts and night shifts have been identified as potentially presenting special risks to pregnant nurses. It is believed that neuroendocrine changes as a consequence of sleep deprivation or disrupted circadian rhythms may affect foetal growth and the timing of delivery. Pregnancy-related complications are major contributors to perinatal mortality and morbidity so identification of modifiable risk factors such as working conditions is an important priority in maternity care.
Two independent meta-analyses reported an adverse effect of shift work on the risk of preterm delivery.
Summary of evidence
Preterm delivery is defined as delivery occurring between 20 and 37 weeks of pregnancy. The possible association between shift work and preterm delivery has been published in several studies. Most of the studies indicated elevated risks, but only two found significantly elevated risks.
Small for Gestational Age
Small-for-gestational age (SGA) is defined as an infant born with a birth weight less than the 10th centile. Ten studies analysed the possible association between shift work and the risk of delivering an SGA baby, including five prospective cohort investigations. Studies tended to rule out a more than moderate effect, an exception being a recent investigation by Abeysena et al. in Sri Lanka which found an RR>3.0 for women exposed to the combination of shift work and other occupational hazards.
Low birth weight
Low birthweight is defined by the World Health Organisation (WHO) as weight at birth of less than
5.5 pounds. The risk of delivering a low birth weight baby has been analysed in several studies. Only one of the three cohort studies showed a significantly elevated risk. Benzene et al, pooled the results of related studies in their meta-analysis and published their findings showing a combined risk estimate of 1.27.
Pre-eclampsia or pregnancy induced hypertension
There are very few studies on this aspect and our research indicates there is currently no empirical evidence to suggest Nurses working shifts are more at risk of of pre-eclampsia or pregnancy induced hypertension.
The mechanisms whereby shift work might result in adverse pregnancy outcomes are not entirely understood. Both direct (through disturbances of circadian rhythm) and indirect (through psychosocial stresses and sleep disruption) mechanisms have been proposed to explain a causal relationship between shift work and obstetric complications that are inherently multifactorial in nature. It is established that shift work modifies peak values and rhythm amplitudes of serum melatonin. Melatonin is known to serve an essential function for a successful pregnancy.
The evidence does not categorically prove that shift work adversely affects pregnancy. That said, the advice of Bonzini et al suggest it would be prudent, in so far as job circumstances allow to permit pregnant women who wish to do so, to reduce their exposure to shift and night working.