Post Maturity

Postmaturity (Prolonged Pregnancy) Post your experience See others (1 there) Postmaturity is defined as: "A pregnancy that exceeds 42 complete weeks (294 days) after last menstrual period (LMP)." Where possible, first trimester ultrasound rather than LMP dating should be relied on to assess pregnancy duration.1 Perinatal risks associated with prolonged pregnancy •

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Beyond around 41 weeks placental function may decline and become insufficient, reducing the supply of oxygen and nutrients to the fetus. Placental insufficiency increases the risk of intrapartum fetal hypoxia. There is also increased risk of meconium aspiration syndrome and neonatal hypoglycaemia. The risk of stillbirth or neonatal death (in healthy women with normal pregnancies) is greater at 42 weeks than 37 weeks. The risk has been shown to be up to 8 times greater at 43 weeks.2,3 The risk of Caesarean delivery and maternal complications also increase with gestational age. There is increased risk of fetal macrosomia, i.e. birth weight > 4 kg and birth injury. Some fetal anomalies, e.g. anencephaly, are associated with prolonged pregnancy. Increased risk of epilepsy in the neonate, particularly if delivered by instrumental delivery or Caesarean section.4

Epidemiology Approximately 7.5% of pregnancies continue to 42 weeks or beyond.5Postmaturity is a syndrome seen in some infants born at or after 42 weeks. However, the term post-mature is often used to describe any infant born after 42 weeks.

Risk factors Previous prolonged pregnancy increases risk of recurrence in subsequent pregnancies two- to three-fold.6 Few pre-natal risk factors are known. However recent work suggests an association with: • • •

BMI > 35.7 Primigravidity. Fish consumption in first 2 trimesters.8

Presentation

Symptoms • • •

When post-mature the neonate has lower than normal amounts of subcutaneous fat and reduced mass of soft tissue. The skin may be loose, flaky and dry. Fingernails and toenails may be longer than usual and stained yellow from meconium.

Signs • • •

Before delivery there may be reduced fetal movement. A reduced volume of amniotic fluid may cause a reduction in the size of the uterus. Meconium-stained amniotic fluid may be seen when the membranes have ruptured.

Investigations Women with no other indications for induction, who do not wish labour to be induced, can be offered monitoring to assess placental function and fetal health. There is a lack of evidence with which to assess the benefits of monitoring and the effectiveness of the various techniques.9 Management Management of prolonged pregnancy in the absence of other complications is controversial: • •

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The Royal College of Obstetricians and Gynaecologists/NICE guidelines recommend that women should be offered induction after 41 weeks.10 Women who decline induction should be offered increased antenatal monitoring from 42 weeks, consisting of twice-weekly cardiotocography (CTG) and ultrasound estimation of single deepest amniotic pool. A pool depth of < 8 cm indicates increased intrapartum risk to the fetus.11 If expectant management is used, some sources recommend labour should be induced at the beginning of the 43rd week.9

However, in a recent randomised trial there were no differences between induced (at 289 days) and monitored groups (every 3 days) in neonatal morbidity, mode of delivery, and general outcome.12 Document references

1. Neilson JP. Ultrasound for fetal assessment in early pregnancy. Cochrane Database of Systematic Reviews 1998, Issue 4. Art. No.: CD000182. DOI: 10.1002/14651858.CD000182. 2. Smith GC; Life-table analysis of the risk of perinatal death at term and post term in singleton pregnancies. Am J Obstet Gynecol. 2001 Feb;184(3):489-96. [abstract] 3. Hilder L, Costeloe K, Thilaganathan B; Prolonged pregnancy: evaluating gestation-specific risks of fetal and infant mortality. Br J Obstet Gynaecol. 1998 Feb;105(2):169-73. [abstract] 4. Ehrenstein V, Pedersen L, Holsteen V, et al; Postterm delivery and risk for epilepsy in childhood. Pediatrics. 2007 Mar;119(3):e554-61. [abstract] 5. Harrington DJ, MacKenzie IZ, Thompson K, et al; Does a first trimester dating scan using crown rump length measurement reduce the rate of induction of labour for prolonged pregnancy? An uncompleted randomised controlled trial of 463 women. BJOG. 2006 Feb;113(2):171-6. [abstract] 6. I Mogren, H Stenlund, U Hogberg. Recurrence of prolonged pregnancy. International Journal of Epidemiology, Volume 28, Number 2, pp. 253-257(5); April 1999 7. Olesen AW, Westergaard JG, Olsen J; Prenatal risk indicators of a prolonged pregnancy. The Danish Birth Cohort 1998-2001. Acta Obstet Gynecol Scand. 2006;85(11):1338-41. [abstract] 8. Olsen SF, Osterdal ML, Salvig JD, et al; Duration of pregnancy in relation to seafood intake during early and mid pregnancy: prospective cohort. Eur J Epidemiol. 2006;21(10):749-58. Epub 2006 Nov 17. [abstract] 9. Briscoe D, Nguyen H, Mencer M, Gautam N, Kalb DB. Management of Pregnancy Beyond 40 Weeks' Gestation. American Family Physician; May 2005 10. NICE (inherited guideline). Induction of labour. July 2008. 11. Dasari P, Niveditta G, Raghavan S; The maximal vertical pocket and amniotic fluid index in predicting fetal distress in prolonged pregnancy. Int J Gynaecol Obstet. 2007 Feb;96(2):89-93. Epub 2007 Jan 22. [abstract] 12. Heimstad R, Skogvoll E, Mattsson LA, et al; Induction of labor or serial antenatal fetal monitoring in postterm pregnancy: a randomized controlled trial. Obstet Gynecol. 2007 Mar;109(3):609-17. [abstract] Internet and further reading •

CEMACH; Saving Mothers' Lives: Reviewing maternal deaths to make motherhood safer 2003-2005; Large PDF.

Acknowledgements EMIS is grateful to Dr Hayley Willacy for writing this article. The final copy has passed scrutiny by the independent Mentor GP reviewing team. ©EMIS 2009. Document ID: 2640 Document Version: 21 Document Reference: bgp208

Last Updated: 15 Jun 2009 Planned Review: 15 Jun 2011

A postmature newborn is delivered after more than 42 weeks in the uterus. • • •

Near the end of a term pregnancy, placental function decreases, providing fewer nutrients and less oxygen to the fetus. Postmature newborns have dry, peeling, loose skin and may appear emaciated because they have not received sufficient nutrition. Some postmature newborns require resuscitation, but generally treatment focuses on providing good nutrition and general care.

Postmature (postterm) delivery is much less common than premature (preterm) delivery. Why a pregnancy continues beyond term is usually unknown. Reduced function of the placenta (the organ that connects the fetus to the uterus and provides nourishment to the fetus) is the greatest risk to fetuses who go beyond term. Near the end of a term pregnancy, the placenta becomes smaller and less effective in providing oxygen and nutrients to the fetus. To compensate, the fetus begins to use its own fat and carbohydrates (sugars) to provide energy. As a result, its growth rate slows, and occasionally weight may even decrease. Postmature newborns are prone to developing low blood sugar levels (hypoglycemia) after delivery because they have exhausted their supply of stored fat and carbohydrates. If the placenta shrinks sufficiently, it may not provide adequate oxygen to the fetus, particularly during labor. A lack of adequate oxygen may result in fetal distress (see Labor and Delivery Complications: Fetal Distress) and, in extreme cases, may result in injury to the brain and other organs. Fetal distress may cause the fetus to pass stools (meconium) into the amniotic fluid. The fetus may also reflexively take deep, gasping breaths triggered by the distress and thereby inhale the meconium-containing amniotic fluid into the lungs before birth. As a result, the newborn may have difficulty breathing after delivery (meconium aspiration syndrome—see Problems in Newborns: Meconium Aspiration Syndrome). Symptoms Postmature newborns have dry, peeling, loose skin and may appear emaciated, especially if the function of the placenta was severely reduced. The fingernails and toenails are long. The umbilical cord and nails may be stained green if meconium was present in the amniotic fluid. Treatment

Postmature newborns who experience low oxygen levels and fetal distress may need resuscitation at birth. If meconium is present in the amniotic fluid and the newborn is lethargic, a tube is passed into the windpipe (trachea) to suction as much meconium as possible from the respiratory tract. If meconium has been breathed into the lungs, a ventilator may be needed to support breathing. Intravenous sugar (glucose) solutions or frequent breast milk or formula feedings are given to prevent hypoglycemia. If these problems do not occur, the major goal is to provide good nutrition so that postmature newborns can catch up to the weight that is appropriate for them.