• For all women taking medication, immediately contact a psychiatrist to establish if drug treatment should be stopped.
• Refer urgently to a psychiatrist and specialist fetomaternal medicine service, for risk assessment and further management, those women who are taking medication with a known teratogenic risk at the time of conception or in the first trimester (i.e. lithium, valproate, carbamazepine, lamotrigine, or paroxetine).
• Refer all other women to a psychiatrist for assessment and a discussion of drug treatment.

• The National Institute for Health and Clinical Excellence recommends:
• That women who have an unplanned pregnancy should stop taking valproate, carbamazepine, and lamotrigine and an alternative prophylactic drug considered (e.g. an antipsychotic).
• If valproate, carbamazepine, or lithium have been prescribed in the first trimester, there should be close consultation with the obstetric team who can provide appropriate screening and counselling.
• Screening for neural tube defects involves maternal serum alpha-fetoprotein estimation (sometimes followed by amniocentesis), and high-resolution ultrasound scanning at weeks 18–23. In the case of lithium, an ultrasound scan can also help identify cardiac anomalies.
• For women taking lithium:
• If the pregnancy is confirmed in the first trimester and the woman is stable, lithium should be stopped gradually over 4 weeks, and the woman informed that this may not remove the risk of cardiac defects in the fetus.
• If the woman remains on lithium during pregnancy, serum lithium levels should be checked every 4 weeks, then weekly from the 36th week, and again less than 24 hours after childbirth. The dose should be adjusted to keep serum levels within the therapeutic range, and the woman should maintain adequate fluid intake.

These recommendations are based on two published guidelines from the National Institute for Health and Clinical Excellence (NICE), Bipolar disorder: the management of bipolar disorder in adults, children and adolescents, primary care and secondary care [National Collaborating Centre for Mental Health, 2006], and Antenatal and postnatal mental health [National Collaborating Centre for Mental Health, 2007].

• Referral:
• All major structural teratogenic effects, including neural tube defects, occur in the first trimester. NICE recommend that all women with bipolar disorder should receive urgent referral to specialist fetomaternal medicine services and women who are taking antiepileptic drugs or lithium in early pregnancy receive screening for major anomalies [National Collaborating Centre for Mental Health, 2006].
• Antipsychotics:
• There is some indication of an increased risk of malformations (2.4%, that is 24 per 1,000). This risk maybe related to the underlying illness (information on individual drugs is very limited) [National Collaborating Centre for Mental Health, 2007]. One small study (n = 151) found no evidence of increased risk. There is little evidence to distinguish between any first- or second-generation antipsychotics. The risk is thought to be considerably less than with other drugs used in the treatment of bipolar disorder. 
• Lithium:
• Lithium is associated with an increased risk of fetal heart defects (risk raised from 8 in 1000 to around 60 in 1000) [National Collaborating Centre for Mental Health, 2007]. Rates of Ebstein's anomaly in particular are raised from 1 in 20,000 to 10 in 20,000.
• Anticonvulsants:
• Carbamazepine is associated with an increased risk of neural tube defects (risk raised from 6 in 10,000 to around 20–50 in 10,000) and other major fetal malformations including gastrointestinal tract problems and cardiac abnormalities [National Collaborating Centre for Mental Health, 2007].
• Lamotrigine is associated with an increased risk of oral cleft defect (risk estimated at nearly 9 in 1000).
• Valproate is associated with:
• An increased risk of neural tube defects (spina bifida and anencephaly; risk raised from around 6 in 10,000 to 100–200 in 10,000).
• Adverse effects on the child's intellectual development.
• Antidepressants:
• There are concerns about a possible increase in the risk of congenital malformation associated with prenatal exposure to selective serotonin reuptake inhibitors (SSRIs) in general, and more specifically with paroxetine. SSRIs taken after 20 weeks of gestation may be associated with an increased risk of persistent pulmonary hypertension in the neonate [National Collaborating Centre for Mental Health, 2007].
• Paroxetine should not be used in pregnancy. Two studies have suggested that, in women taking paroxetine in the first trimester, the risk of congenital malformation may increase from 3% to around 4%, with an increase in risk from about 1% to 2% for congenital heart malformations [MHRA, 2005].
• Fluoxetine is the SSRI with most evidence of safety in pregnancy, and remains the first-line SSRI for use during pregnancy [NTIS, 2005].
• Tricyclic antidepressants, such as amitriptyline, imipramine, and nortriptyline, have lower known risks during pregnancy than other antidepressants. However they are more likely to be associated with precipitating mania.
• Benzodiazepines:
• Benzodiazepines should not be routinely prescribed for pregnant women, except for the short-term treatment of extreme anxiety and agitation. This is because of the risks to the fetus (e.g. cleft palate) and the neonate (e.g. floppy baby syndrome).