The Committee forward Practice Bull...

The Committee forward Practice Bulletins--Obstetrics of the American society of Obstetricians and Gynecologists has released a fresh guideline entitled, "Management of Postterm Pregnancy." The guideline appears in the September 2004 issue of Obstetrics and Gynecology and is available online at http://www.greenjournal.org/cgi/reprint/104/3/639.

Postterm pregnancy, on definition, refers to a pregnancy that has stretch outed to or beyond 42 weeks of gestation. Accurate pregnancy dating is critical to the diagnosis. The word "postdate" is poorly defined and should be avoided. Although a certain number of cases of postterm pregnancy likely eventuate from an inability to accurately define the estimated date of delivery, many cases spring from a true prolongation of gestation. The reported oftenness of postterm pregnancy is approximately 7 percent

When postterm pregnancy really exists, the cause usually is unknown. Primiparity and prior postterm pregnancy are the greatest in number common identifiable risk factors for prolongation of pregnancy. Rarely, postterm pregnancy may be associated with placental sulfatase deficiency or fetal anencephaly.

Postterm pregnancy is associated with significant risks to the infant. The perinatal mortality rate at more than 42 weeks of gestation is twice that at confine and increases sixfold and higher at 43 weeks of gestation and beyond. Uteroplacental insufficiency, meconium aspiration, and intrauterine infection contribute to the increased rate of perinatal mortality. Postterm pregnancy also is an independent risk factor for cheap umbilical artery pH levels at delivery and reasonable five-minute Apgar scores. For these reasons, the turn has been toward delivery according to 41 completed weeks of gestation.

Although postterm infants are larger than boundary infants and have a higher incidence of fetal macrosomia, no evidence supports inducing labor as a preventive measure in like cases, according to the guideline. Complications associated with fetal macrosomia include protracted labor, cephalopelvic disproportion, and shoulder dystocia with resultant risks of orthopedic or neurologic injury.

Approximately 20 percent of postterm infants have dysmaturity syndrome which respects to infants with characteristics resembling chronic intrauterine putting out restriction from uteroplacental insufficiency. These pregnancies are at increased risk for umbilical cord compression from oligohydramnios, meconium aspiration, and short-term neonatal complications, and have an increased incidence of nonreassuring fetal testing.

Infants born postterm also are at increased risk of death within the first year of life, although a certain of these infant deaths clearly flow from peripartum complications (such as meconium aspiration syndrome)

There are significant risks to the pregnant woman as well, including an increase in labor dystocia, an increase in censorious perineal injury related to macrosomia, and a doubling in the rate of cesarean delivery. Cesarean delivery is associated with higher risks of complications, in the same state [i]or[/i] condition as endometritis, hemorrhage, and thromboembolic disease. Finally, postterm pregnancy can be a source of substantial anxiety for the pregnant woman.

Summary of Recommendations

The following recommendations are based upon good and consistent scientific evidence (Level A):

* Women with postterm gestations who have unfavorable cervices can meet with labor induction or be managed expectantly.

* Prostaglandin can be used in postterm pregnancies to elevate cervical ripening and induce labor.

* Delivery should be imported if there is evidence of fetal compromise or oligohydramnios.

The following recommendations are based primarily forward consensus and expert opinion (Level C):

* Despite a lack of evidence that monitoring improves perinatal issue it is reasonable to initiate antenatal surveillance of postterm pregnancies between 41 weeks (287 days; estimated delivery date + 7 days) and 42 weeks (294 days; estimated delivery date + 14 days) of gestation because of evidence that perinatal morbidity and mortality increase as gestational age advances.

* Many physicians use twice-weekly testing with a certain evaluation of amniotic fluid mass beginning at 41 weeks of gestation. A nonstress criterion and amniotic fluid volume assessment (a modified biophysical profile pBPP]) should be adequate.

* Many authorities commit prompt delivery in a postterm patient with a favorable cervix and no other complications.

COPYRIGHT 2004 American Academy of Family Physicians

COPYRIGHT 2004 Gale Group