Prolonged Pregnancy

A small percentage of pregnancies will continue beyond 42 weeks (294 days after the last menstrual period). There have been cases in which pregnancy extended to 336 and 337 days, and one in which the duration was 343 days (49 weeks). Estimates vary that from 2 percent to more than 10 percent of all pregnancies will not have delivered by 42 weeks gestation. This statistic reflects some errors in dating pregnancies rather than pregnancies that actually exceed 42 weeks. For example, if a woman doesn’t exactly remember her last menstrual period, or when the timing between a woman’s periods is longer than 28 days, and this isn’t accounted for when initially deciding the due date, her calculated delivery date may be off by several weeks. To prevent a miscalculation of pregnancy dates, all women should:

• Keep track of the first day of every menstrual period so you always know your last one should you become pregnant.
• Have a preconception care visit several months before planning a pregnancy
• Seek early prenatal care as soon as you believe you are pregnant.

The Effect of Prolonged Pregnancy on the Fetus

When a pregnancy is genuinely prolonged beyond 42 weeks, there is a chance that the welfare of the fetus may be jeopardized, Prolonged pregnancy may result in a condition known as placental deficiency or uteroplacental insufficiency-in which the placenta ceases 1:0 function well enough to supply the fetus with needed oxygen. Many such fetuses tolerate the stress of labor poorly. They often ‘lave diminished amniotic fluid, decreasing the cushion they need to Withstand contractions, They are prone to pass meconium (the thick green material that fills the fetal large intestine) into the amniotic fluid, making a dense mixture, They tend to gasp in response to the stress of uterine contractions and thus to breathe in the meconium, Meconium is very irritating to the lung tissue and breathing it in can “result in respiratory difficulty after birth.

Some babies born after 42 weeks gestation develop “post maturity ­syndrome.” These babies lose some of the fat under their skin so they appear thin, Their fingernails are characteristically long, They often lose the protective creamy coating on the skin called vernix caseosa, as well as the fine hair covering the newborn’s body, called lanugo. This makes their skin dry, peeling, and unusually wrinkled, They are born with an especially alert look.

When pregnancy is prolonged, with the possibility of post maturity a number of tests are utilized to check the baby’s well-being.These tests are fully described in Chapter 17. When midwives or family physicians have been the primary providers for the pregnancy,an obstetrician should be consulted after 42 weeks. If there is any question about whether the baby is in danger, labor usually will be induced.

Cesarean delivery is not a treatment for a postdates pregnancy unless fetal assessment has given evidence of serious fetal distress, indicating that induction will be dangerous to the fetus, or when a planned induction does not succeed,