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Post term Pregnancy. Definitions:. postdates pregnancy - patient who has not delivered by end of 42nd week or 294 days from first day of last menstrual period (LMP) prolonged pregnancy - exceeds 40 weeks (280 days) from known time of ovulation. Incidence:.
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Definitions: • postdates pregnancy - patient who has not delivered by end of 42nd week or 294 days from first day of last menstrual period (LMP) • prolonged pregnancy - exceeds 40 weeks (280 days) from known time of ovulation
Incidence: • 27 percent of pregnancies deliver in the 40th and 41st week . • 5.5 percent deliver at ≥42 weeks.
Incidence: • pregnancies dated by first trimester ultrasound examination: • ≥41 weeks ranges from 5 to 11 percent • ≥42 weeks is about 2 percent
Causes: • The commonest cause is error in calculation of gestational age. • Congenital anomalies like anencephaly which disrupt foetal pitutary adrenal axis and rare maternal enzyme deficiencie(placental sulphatase. • In most cases cause is not known.
Risk Factors • Maternal or paternal personal history of postterm birth • Nulliparity • Male fetus • Maternal obesity • Older maternal age • lower socioeconomic groups
Pathogenesis: • amniotic fluid volume decreases • amniotic fluid volume reaches maximum at 24 weeks, constant until 37 weeks, then decreases • decreased amniotic fluid volume associated with decreased fetal movement and fetal heart rate decelerations
A. Fetal Complications • Still birth rate increases significantly at term with advancing gestation. • It is 0.35/1000 pregnancies at 37 weeks • While 2.12/1000 pregnancies at 43 weeks.
Meconiumaspiration • Macrosomia • Asphyxia before, during and after delivery • Fractures and Peripheral nerve injury • Pneumonia • Septicaemia • Intra cranial hemorrhage
Dysmaturity(postmaturity syndrome) • Incidence 20% • stage 1 - alert facial expression; recent weight loss with decreased subcutaneous fat and muscle mass • stage 2 - green meconium staining of skin and umbilicus, fetal distress, hypoxia • stage 3 - yellow staining of nails, skin and umbilicus indicative of prolonged passage of meconium
B. Maternal Complications • cesarean delivery • rates of primary cesarean delivery • 8.2% at 38 weeks • 8.8% at 39 weeks • 9% at 40 weeks • 14% at 41 weeks (p < 0.001) • 21.7% at ≥ 42 weeks (p < 0.001)
operative vaginal delivery • 8.8% at 38 weeks • 9.4% at 39 weeks • 10.9% at 40 weeks (p < 0.001) • 13.3% at 41 weeks (p < 0.001) • 17.4% at ≥ 42 weeks (p < 0.001)
postpartum hemorrhage, starting at 38 weeks • third- or fourth-degree laceration, starting at 39 weeks • prolonged labor (> 24 hours), starting at 39 weeks • chorioamnionitis, starting at 40 weeks • endomyometritis, starting at 41 weeks
Induction versus expectant management: • compared with delivery induction, expectant management associated with • decreased mortality risk at 37 weeks gestation (relative risk [RR] 0.87. 95% CI 0.77-0.99) • similar mortality risk at 38 weeks gestation (RR 1.11, 95% CI 1-1.22) • increased mortality risk at • 39 weeks gestation (RR 1.47, 95% CI 1.35-1.59) • 40 weeks gestation (RR 1.58, 95% CI 1.45-1.71) • 41 weeks gestation (RR 1.63, 95% CI 1.47-1.81) Reference - Obstet Gynecol 2012 Jul;120(1):76
Prevention: • Recording LMP and calculating EDD at the time of first ANC visit. • Routine early ultrasound for dating of pregnancy. • Review of antenatal card and ultra sonographic reports in terms of fetal growth. • Sweeping of membranes from 38 wks onwards decreases number of pregnancies going beyond 41 and 42 wks. • As soon as prematurity is ruled out in high risk cases induction of labour will prevent post maturity.
