21st March 2024

Pregnancy and breastfeeding

Background

During all stages of preconception, pregnancy, labour and breastfeeding there is the potential for drugs to cause harm. During pregnancy the smallest effective dose of a drug should be prescribed, and only if the maternal benefit outweighs the foetal risk. It is recommended to take high dose folic acid before conception and during the first trimester.

Analgesia

Paracetamol is the first line option. Opioids can be used in the short term treatment of moderate to severe pain where paracetamol has not been effective. NSAIDs typically are avoided but can be used in the first or second trimester, they must be avoided in the 3ʳᵈ trimester due to the risk of closure of the fetal ductus. There is limited evidence of gabapentinoids in pregnancy.

Antihypertensives

The first line treatment is oral labetalol, alternatives are nifedipine and methyldopa. For women with hypertension (chronic or previous gestational), diabetes mellitus, autoimmune disease or CKD – aspirin is recommended from week 12 of pregnancy. Females already taking ACE inhibitors, thiazide/thiazide-like diuretics or angiotensin II receptor blockers (ARBs) should have these medications stopped and specialist opinion sought.

Antihyperglycaemics

In certain cases where the benefits of adequate blood glucose control outweigh the risks of harm, metformin can be continued for the pre-conception period and during pregnancy. Women with gestational diabetes who present with fasting plasma glucose of above 7 mmol/litre should be immediately started on insulin with or without metformin in combination with lifestyle advice.

Antiepileptics

NICE recommends lamotrigine and levetiracetam as the safer antiepileptics in pregnancy as monotherapy. Sodium valproate, phenytoin, topiramate, phenobarbital and carbamazepine are all associated with an increased risk of congenital abnormalities.

Antibiotics

The main antibiotic options throughout pregnancy involve penicillins and cephalosporins. Nitrofurantoin is safe throughout pregnancy except at term due to haemolytic anaemia in the neonate. Trimethoprim is only considered safe after the first trimester.

Breastfeeding

Many drugs given to lactating women are detectable in breast milk. The concentration is usually low however several drugs have significant effects on the nursing infant. BNF recommends continually checking the breastfeeding section for every drug as the data is constantly changing.

References

• Bnf.nice.org.uk. 2022. Prescribing in the elderly, hepatic impairment, renal impairment, pregnancy| Medicines guidance | BNF content published by NICE. [online] Available at: https://bnf.nice.org.uk/medicines-guidance
• Bnf.nice.org.uk. 2022. Hypertension, epilepsy, diabetes, pregnancy and breast feeding | Treatment summaries | BNF content published by NICE. [online] Available at: https://bnf.nice.org.uk/treatment-summaries
• Bisson, D., Newell, S. and Laxton, C., 2018. Antenatal and Postnatal Analgesia. BJOG: An International Journal of Obstetrics & Gynaecology, 126(4).