What happens when your “due date” has passed by and you have not delivered your baby? For many pregnant women, the “due date” comes and goes causing anxiety, frustration with the discomforts of pregnancy, and a daily juggle of work schedules and babysitters. The “late term” pregnancy, which is going past your 40th completed week of gestation, can happen to anyone -- whether it is your first or ninth pregnancy. There is no way of knowing when you will go into labor. It is a hormonal trigger we do not fully understand that softens the cervix and initiates contractions.

Ovulation, conception, cycle differences, environmental influences, hormonal responses, maternal and fetal health and more, impact the onset of labor. The Estimated Date of Confinement (EDC) is an estimate. Calculation dates back to Naegele’s rule in 1805 based on a last menstrual cycle of 28 days assuming that a routine pregnancy is 280 days long. Many women have irregular cycles and the months of the year are not equal, so the EDC is an educated guess. Dating the pregnancy accurately in the first trimester either by a certain last menstrual date, accounting for long cycles and conception, or an ultrasound, if necessary due to poor dating criteria, does help at the end of pregnancy with decision making concerning how long to wait to ensure that the pregnancy is really postdate.

A postdate pregnancy  is defined as a pregnancy lasting more than 294 days, or 42 completed weeks after the first day of the last menstrual cycle. According to many authors and the National Birthday Trust data, perinatal mortality and morbidity increase after the 42nd week and quadruple in the 44th week. According to the chapter on Postdatism in the Global Library of Women’s Medicine, “the threshold of 42 weeks became established because the incidence of macrosomia, oligohydramnios, meconium aspiration, and caesarean section performed for fetal distress are significantly increased after 42 weeks gestation.” Accurate dating of the pregnancy in the first trimester ensures unnecessary inductions before 42 weeks.

Obstetrical providers vary on their approach to management of pregnancy at term and postdates. There is growing public awareness of the high incidence of induction at term and before 40 weeks of healthy women. This practice leads to unnecessary medical complications, failed inductions adding to increased spending of healthcare dollars, labor interventions and higher rates of Caesarean sections in this group of patients. It is important for the pregnant woman to be knowledgeable about what is truly medically necessary and what might be an opinion in practice management.

My nurse-midwifery approach is expectant management. This is acting within standard protocols characterized by being watchful and waiting. It is best described as being vigilant about watching for signs that the baby should be delivered, while not intervening if all the data is normal. Healthy, pregnant women will be asked to continue their high protein, nutritional diet with lots of water, stay active by walking 30 minutes a day or practicing yoga, and achieve adequate rest.

In addition they will be advised to follow these steps to ensure that the pregnancy should continue and await spontaneous labor:  daily kick counts; weekly prenatal visits; and biweekly non-stress tests starting at 41 weeks gestation. The non-stress test is performed using the external fetal monitor to capture the baby’s movements while listening to the baby’s heart rate in response. The accelerations in the fetal heart rate are reassuring that the fetus is doing well. 

A biophysical profile, which is an ultrasound to check the amount of amniotic fluid and fetal status, can also be used based on clinical judgment. One reason to perform the ultrasound would be a woman with an unripe cervix approaching 42 weeks which would make an induction very difficult. If mom and baby are well, the pregnancy could continue a few more days with daily monitoring to allow for the hormones to soften the cervix.

Labor will happen 90% of the time if we do not interfere. It is best for both mother and baby in a healthy pregnancy to await spontaneous labor. Induction is offered at 42 weeks with options of cervical ripening and the least amount of intervention to achieve delivery.