Effects of Sleep, Fatigue, and Timing of Post-Dates Inductions among Nulliparas

Today, nearly 1 in 4 births in the United States (US) are induced, a rate more than twice that of 20 years ago. Unsuccessful inductions lead to cesarean deliveries, and there is evidence that the increase in induced births is contributing to the increasing cesarean rate. Cesarean deliveries increase both the short-term and long-term morbidity for women and their infants. Therefore, research that contributes to making inductions as successful as possible should be a priority.

Only four studies worldwide, and no US studies, have examined the relationship between the time of day induction begins and obstetrical outcomes, and those four had conflicting results. However, there are reasons to believe that inductions initiated in the evening may affect circadian rhythms and in turn, induction outcomes, and that induction times might best be tailored to personal chronobiology.

Sleep has powerful physiological effects, including regulation of neurotransmitters and pituitary hormones which play a role in labor. It is already known that sleep and fatigue affect labor outcomes. For example, Lee and Gay showed that among nulliparous women, those who obtained less than 6 hours of sleep in the month prior to the onset of labor or labor induction had 4.5 times the odds of having a cesarean birth. There is a definite circadian rhythm to uterine contractions, with labor onset beginning more frequently in the evening and early morning hours between 2000 and 0200. Individuals have their unique chronobiology, with some people clearly being ‘morning larks’ and others being ‘evening owls’, and this chronotype affects sleep timing and circadian hormones.

Inductions, particularly those indicated for post-dates (after 40 weeks gestation), are scheduled interventions, unless the fetus is in immediate distress. Thus, good research on optimal times for induction could readily influence the scheduling of inductions and thus improve outcomes.

Using the population of Community Regional Medical Center in Fresno, California, we plan a randomized clinical trial to study nulliparas undergoing post-dates inductions in the morning and the evening for potential predictive factors for successful induction (vaginal birth within 24 hours of admission) and for adverse obstetrical outcomes, especially cesarean birth. The aims of this pilot, randomized clinical trial is to:

1. Describe the extent to which the following factors predict birth within 24 hours:

a. morning versus evening chronotype;

b. self-reported duration and quality of sleep during the month prior to induction;

c. self-reported fatigue severity on admission for induction;

d. hand grip strength, a physiological measure of muscle fatigue, at induction admission.

2. Describe differences in labor interventions and modes of delivery for inductions that start in the evening compared to the morning.

3. Determine the extent to which time of day induced (morning versus evening), affects change in fatigue scores and hand strength from admission baseline to onset of labor.

In addition to achieving these aims, effect sizes for the various measures will be calculated and used to design an R01 randomized clinical trial with a large sample sufficiently powered to detect statistical significance.