“Pregnant women carry varying definitions of ‘full term’ and hold different opinions regarding the safety of delivery at various gestational ages,” write the authors of an article published in the December 2009 issue of Obstetrics and Gynecology.

The rate and absolute number of late preterm births (34-36 weeks of gestation) and early term births (37-38 weeks of gestation) are increasing. Births after induction of labor and cesarean delivery before labor appear responsible for much of the increase in preterm and early term births.

However, the reasons for the choice of timing of these deliveries have not been well studied. When choosing when to deliver, women’s perceptions of the gestational age that defines preterm and whether prematurity poses health risks are likely to be important factors.

In a recent survey commissioned by United Healthcare (a national health benefits provider) to estimate women’s attitudes related to cesarean and induced delivery, several questions were asked related to women’s beliefs about the definition of “full term” and the safety of delivery at various gestational ages. The article presents survey findings on women’s understanding of the definition of “full term” and the gestational age at which it is safe to deliver during an otherwise healthy pregnancy.

First-time mothers ages 21-45 were selected at random from a national database of women who had given birth within the past 18 months. Those who had a medical condition that would put them at high risk for a cesarean delivery were excluded from the study.

The survey explored the relationship between respondents’ perceptions of the gestational age at which a birth becomes full term and the earliest gestational age at which they believed an infant can be delivered safely. The analysis also assessed whether participants’ responses to the question on the gestational age they considered “full term” and “safe to deliver” varied by their socio-demographic characteristics.

The authors found that:

* 650 women completed the survey.

* When asked “at what gestational age do you believe the baby is considered full term?” (with possible responses ranging from 34 to 40 weeks of gestation), 24.1 percent of the respondents chose 34-36 weeks, 50.8 percent chose 37-38 weeks, and 25.2 percent chose 39-40 weeks.

* Compared with women ages 21-29, women ages 30-39 were more likely to choose 34-36 weeks of gestation as the definition of “full term,” as were single women compared with married women. Compared with women employed outside the home, those not employed outside the home were less likely to choose 34-36 weeks of gestation as the definition of “full term.”

* When asked “what is the earliest point in the pregnancy that it is safe to deliver the baby, should there be no other medical complications requiring early delivery?” (also with the range of choices from 34-40 weeks of gestation), more than half of the women selected 34-36 weeks of gestation as their response. In contrast, fewer than one in four selected either 37 weeks or 38 weeks. Fewer than 10 percent chose 39-40 weeks.

* Compared with white women, Asian women were less likely to choose 34-36 weeks of gestation, as were women with a high school education or a college education compared with women with a graduate education.

* The gestational age at which the women had delivered their infant significantly correlated with the gestational age at which they considered their infant full term and the gestational age at which they considered it safe to deliver. However, the association between the variables was relatively weak.

* There was a significant correlation between the gestational age at which women considered their infant full term and the earliest gestational age that they considered it safe to deliver, showing a moderately strong relationship.

“With the trend of an increased patient role in medical decision-making, ensuring that women understand the implications of the timing of delivery may be an important component of interventions to reduce the number of elective or semi-elective late preterm and early term deliveries,” conclude the authors.