Both acetaminophen (paracetamol) and opioid analgesics cross the placenta. Epidemiologic studies have shown acetaminophen (paracetamol) has been used in humans without apparent harmful effects. Codeine has not shown teratogenic effects in rats and rabbits when administered during the period of organogenesis in doses ranging from 5 to 120 mg/kg. Doses of 120 mg/kg in the rat (toxic range) were associated with an increase in embryo resorption at the time of implantation. A single 100 mg/kg subcutaneous codeine dose resulted in delayed ossification in offspring. The use of codeine during labor may cause respiratory depression in the newborn infant. Prolonged use of opioids during pregnancy can result in physical dependence in the neonate and neonatal opioid withdrawal syndrome shortly after birth. The onset, duration, and severity of the condition will vary based on use (duration of use, timing, and amount of last maternal use) and rate of elimination in the newborn. There are no controlled data in human pregnancy.

Chronic use of opioids may cause reduced fertility; it is unknown whether these effects are reversible.

AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

US FDA pregnancy category C: Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Use is not recommended unless the benefit outweighs the risk to the fetus

AU TGA pregnancy category: A
US FDA pregnancy category: C

Comments: Prolonged use of opioids during pregnancy can result in physical dependence in the neonate; women should be advised of the risk of neonatal abstinence syndrome and ensure that appropriate treatment will be available.

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Acetaminophen (paracetamol) is present in breast milk in quantities much less than doses usually given to infants. Codeine is present in breast milk and for women with normal codeine metabolism (normal CYP450 2D6 activity) the amount of codeine secreted is low and dose-dependent; however, in women who are ultra-rapid metabolizers of codeine (those with a specific CYP2D6 genotype) higher-than-expected serum levels of morphine, codeine's active metabolite, may be present in breast milk which may lead to dangerously high serum morphine levels in their breastfed infants. In most cases, a person's specific CYP2D6 genotype is unknown. Several small series and 1 small retrospective study suggest that codeine may be causative in episodes of apnea, bradycardia, and cyanosis in the first week of life. A death of a breastfeed infant due to respiratory depression has been reported; the mother was found to be a CYP450 2D6 ultrarapid metabolizer.

Not recommended

Excreted into human milk: Yes

Comments:
-Breastfeeding is not recommended due to the risks of serious adverse reactions in breastfed infants such as excess sleepiness, difficulty breastfeeding, and serious breathing problems that may result in death.

See references