Women must be careful about what they consume during pregnancy because many substances cross the placental barrier and enter the bloodstream of the unborn baby. Same applies to breastfeeding mothers. Some drugs cross the placenta, or enter breastmilk easily, reaching considerable concentrations in the fetus/baby, while others do not cross due to their larger molecular structures.
As a general rule, women within the reproductive age group (15 to 49), who are sexually active should ensure that they exclude pregnancy before they ingest any drug.
If you are planning to get pregnant, you should stay away from over-the-counter drugs except folic acid and other vitamins, which are, in fact required for healthy mother and baby. If you are already pregnant, ask your doctor about the safety of any prescribed drug and weigh the risks and benefits.
Furthermore, the safety of certain drugs vary from one trimester to another. Some drugs may be stopped just before, and at the beginning of pregnancy because of the higher risk of damage to the fetus during the critical period of development (first 8 – 9 weeks). Other drugs should be discontinued towards the end of pregnancy as their effect on the mother/fetus become more marked at that time.
If the risk of taking the drug outweighs the benefit to mother and/or child, then you should ask for an alternative drug or possibility of delaying the treatment until delivery. If you are on a long-term treatment for any chronic disease, you may need to modify the type or dose of the drug you are using. If the drug carries serious risks but you must continue it for your own health, then you should consider a long-term or permanent method of contraception.
In terms of risk to the baby, drugs have been classified into 5 categories –
*Category A – Generally acceptable. Controlled studies in pregnant women show no evidence of risk to the foetus. Eg. Folic acid.
*Category B – May be acceptable. Human studies not available or minor risk reported in animal studies. Eg. Paracetamol.
*Category C – Use with caution if benefits outweigh risks. No human studies done. Eg. Antifungals like clotrimazole.
*Category D – Use in life-threatening emergencies, when no safer drug is available. Studies have shown evidence of fetal risks. Eg. Aspirin.
*Category X – DO NOT USE IN PREGNANCY. Risks involved outweigh potential benefits. Safer alternatives exist. Eg. Warfarin.
Social drugs such as alcohol, tobacco, or cannabis all pose significant risks to the developing fetus. Women who are addicted to these drugs must be managed by experts before and throughout pregnancy and puerperium.