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Prolonged Pregnancy

Term pregnancy: 37-42 weeks from last menstrual period

Postterm or postdates: greater than 42 weeks

Incidence

Preterm: 10%

38-42 weeks: 80%

42 weeks: approximately 10% (3-12% various studies)

Exactly 40 weeks: 5 %

Beyond 43 weeks: 4 % prolonged,

GESTATIONAL DATING

Many patients are erroneously dated

Late ovulation

Poor history

Inaccurate ultrasound (US) changes

US and gestational dating

Don't change dates if variation < US accuracy (gestational age dependent)

Never replace early SOhO EDD with later sono: risks missing IUGR or wrongly diagnosing in large fetus

Fetus: increased likelihood of

Oligohydramnios

Meconium passage/aspiration

Macrosomia/shoulder dystocia

Fetal distress: 3x rate of low APGARs

Fetal demise: increases after 41 weeks

Anencephaly

Maternal: 3--4x C-section rate secondary to cephalopelvic disproportion and fetal distress postterm, past due, late

Obstetrician: a leading cause of malpractice litigation in the United States

PERINATAL MORBIDITY AND MORTALITY