Table of Contents
Overview
Post-term pregnancy refers to a pregnancy that continues beyond 42 weeks gestation. It carries increased risks to both mother and fetus due to declining placental function, leading to complications such as macrosomia, dystocia, and fetal distress. Understanding the causes, clinical features, and management strategies is essential for reducing perinatal morbidity and mortality in prolonged pregnancies.
Definition
- Ongoing pregnancy that extends beyond 42 weeks gestation
Aetiology
- Most commonly idiopathic
- Fetal anencephaly (absence of fetal pituitary gland → no ACTH surge → delayed labour)
- Placental sulfatase deficiency (rare, X-linked recessive disorder affecting oestrogen synthesis)
Epidemiology
- Affects approximately 5.5% of all pregnancies
Clinical Features
- Post-maturity syndrome:
- Foetal weight loss
- Decreased subcutaneous fat
- Long, thin body
- Overgrown nails
- Dry, peeling (desquamating) skin
- Increased risk of:
- Placental insufficiency
- Macrosomia
- Labour dystocia
- Fetal distress
Management
- At 39 weeks with maternal age >40 → Consider induction of labour
- 40–41 weeks → Continue with expectant management
- >41 weeks → Offer or strongly consider induction of labour
- If Amniotic Fluid Index (AFI) is low → Proceed with induction
Prognosis
- Associated with a 2–3x increased risk of perinatal mortality
- This is primarily due to progressive uteroplacental insufficiency leading to hypoxia or stillbirth
Summary
Post-term pregnancy is defined as gestation beyond 42 weeks and is linked to increased fetal and maternal risks, including placental insufficiency, macrosomia, and dystocia. Early recognition and timely induction of labour are key to preventing complications. For more, visit our Obstetrics Overview page.