Prolonged pregnancy is defined as pregnancy which progresses beyond 42 weeks. It is associated with fatal, neonatal, and maternal complications. Risks increase after term and significantly so after 41 weeks of pregnancy. According to Dr. Max Mongelli, induction of labour appears to improve outcomes and reduce perinatal mortality. Where possible, first trimester ultrasound rather than last menstrual period dating should be relied on to assess pregnancy duration. This should be determined using crown-rump measurement or head circumference if crown rump length is above 84mm.
Tests are used to monitor the health of a post term feteus and to determine whether it is safe to allow the pregnancy to continue or not.
Risks associated with post-term pregnancy
1) Fetal and neonatal risks
Post term pregnancy is associated with an increase in perinatal and mortality. There is an increased risk of still birth and neonatal death, as well as increase in risk of death in 1st year of life. The increased mortality is thought to be due to factors such as ultero- placental insufficiency, meconium aspiration and intrauterine infection.
Foetal morbidity also has higher risks of neonatal acidaemia and low five minute apgar scores, as well as the meconium aspiration. It can results in birth injury, and neonatal seizures.
Maternal risks
Tests are used to monitor the health of a post term feteus and to determine whether it is safe to allow the pregnancy to continue or not.
Risks associated with post-term pregnancy
1) Fetal and neonatal risks
Post term pregnancy is associated with an increase in perinatal and mortality. There is an increased risk of still birth and neonatal death, as well as increase in risk of death in 1st year of life. The increased mortality is thought to be due to factors such as ultero- placental insufficiency, meconium aspiration and intrauterine infection.
Foetal morbidity also has higher risks of neonatal acidaemia and low five minute apgar scores, as well as the meconium aspiration. It can results in birth injury, and neonatal seizures.
Maternal risks
- There are increased risks for the mother, including:
- Obstructed labour
- Perineal damage
- Caesarean damage
- Instrumental vaginal delivery
- Postpartum haemorrhage
- Infection
Where labour is induced before the uterus or cervix are in a favourable state, obstetric problems may follow which can have an adverse effect on mother or baby, including:
- Need for c-section delivery
- Prolonged labour
- Traumatic delivery
- Postpartum haemorrhage
Risk factors
- Previous post term pregnancy increases the risk of recurrence of subsequent pregnancies.
- Primigravidity
- High maternal BMI is associated with longer gestation and increased rate of induction of labour. Elevated pre- pregnancy weight and maternal weight gain both increase the risk of a post term delivery.
- There is an increased risk for mothers who were themselves born post term, and twin studies also suggest a genetic role
- Advanced maternal age
