Understanding of the occurrence and severity of likely neonatal complications is important when planning antenatal care and birth, and in counselling parents. Babies of women with diabetes should remain with their mothers unless there is a clinical complication or there are abnormal clinical signs that warrant admission for intensive or special care. Combined maternal and fetal hypothyroidism is associated with abnormal neurodevelopmental outcome. The most severely affected babies have mental restriction and motor impairment. Babies of mothers with epilepsy have a two- to three-fold higher risk of congenital malformations, mainly associated with antiepileptic drugs. Clinical management of psychiatric illness during pregnancy and lactation encompasses an assessment of the risk of exposure of the mother and neonate to medication during pregnancy. Maternal bacterial infection may be associated with poor condition at birth and neonatal bacteraemia or meningitis with a risk of long-term neurological sequelae or even death.