What is the Definition of a “Term Pregnancy?”

For years, obstetric opinion (shared by nurse-midwives) has been that “term” pregnancy refers to one at from 37 to 42 weeks completed gestation, starting with the date of the last menstrual period.  Babies born within this five-week window were thought to be out of danger of complications of “prematurity” or “post-maturity.”  However, particularly with the recent propensity to induce labor in women before 39-40 weeks, particularly when that induction is not for medical or obstetric reasons but for the convenience of the woman or the provider, the number of adverse outcomes to babies has been climbing upward.  As it turns out, babies born before 39 weeks are different from babies born later; they are more likely to have breathing problems, to require longer stays in the hospital, and, as they grow, to have problems with hearing and with learning.  Recent research has shown that those last few weeks in the uterus are important for babies; for example, their brains grow by up to a third and they develop a fat layer under the skin, helping them to maintain their body temperature after birth.  As they see their nurseries and NICUs fill up with these babies, many hospitals are now moving to limit early inductions to those that are done to manage a serious medical condition in the mother or the baby.

To address this lack of uniformity, the American College of Obstetricians and Gynecologists convened a work group in late 2012.  This group  cam up with a Committee Opinion on the Definition of Term Pregnancy which “recommended that the label “term” be replaced with the designations early term (37 0/7 weeks of gestation through 38 6/7 weeks of gestation), full term (39 0/7 weeks of gestation through 40 6/7 weeks of gestation), late term (41 0/7 weeks of gestation through 41 6/7 weeks of gestation), and postterm (42 0/7 weeks of gestation and beyond) to more accurately describe deliveries occurring at or beyond 37 0/7 weeks of gestation.

“The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine endorse and encourage the uniform use of the work group’s recommended new gestational age designations by all clinicians, researchers, and public health officials to facilitate data reporting, delivery of quality health care, and clinical research.”

This new definition, which depends not on an entire five-week period but on specific designations within that window, should make providers and women stop and think before going ahead with that elective induction, even if their hospital would permit it.  It’s not nice to fool Mother Nature, and it’s foolhardy to hurry her up as well.