-Some experts say that acetaminophen-caffeine should not be taken during pregnancy due to the risk of lower birth weight and spontaneous abortion associated with caffeine consumption.
-Two cases of acetaminophen overdose in late pregnancy have been reported. In both cases neither the neonate nor the mother suffered hepatic toxicity.
-Caffeine levels in fetal blood and tissue have been similar to those in the mother.
-Caffeine has been reported to be an animal teratogen; however, only with doses high enough to cause toxicity in the mother.
-In a study of 2817 fertile women, no evidence of adverse effects from caffeine was found. The fecundability ratio (adjusted for known risk factors for time to conceive) was 1.03 between fertile women who consumed more than 7000 mg caffeine per month and those who consumed 500 mg or less per month. Caffeine was not associated with infertility in 1818 infertile women. In another study (n=441) no evidence was found that moderate caffeine use increased the risk of spontaneous abortion, intrauterine growth retardation, or microcephaly.

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 B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.

(AU, UK): Use is not recommended.
(US, CA): This drug should be used during pregnancy only if clearly needed.

AU TGA pregnancy category:
-Paracetamol: A
-Caffeine: Not formally assigned to a pregnancy category.
US FDA pregnancy category:
-Acetaminophen: Not formally assigned to a pregnancy category.
-Caffeine: B

Comments:
-Acetaminophen is routinely used for short-term pain relief and fever in all stages of pregnancy. It is believed to be safe in pregnancy when used intermittently for short durations.
-Caffeine crosses the placenta. Both human and animal studies have failed to reveal evidence of significant mutagenic or carcinogenic effects.

See references

(AU, UK):
Use is not recommended due to the caffeine content.

(US, CA):
Acetaminophen is considered compatible with breast-feeding by the American Academy of Pediatrics. Because caffeine is excreted into human milk and because caffeine is metabolized slowly by nursing infants, consumption of more than moderate levels of caffeine by nursing mothers is not recommended.

Excreted into human milk: Yes (acetaminophen, caffeine)

Comments:
-Adverse effects in the nursing infant are unlikely. However, irritability and poor sleep patterns have been reported in nursing infants from the caffeine component.

Acetaminophen is excreted into human breast milk but in clinically insignificant amounts. One small study has reported that following a 1000 mg dose of paracetamol to nursing mothers, nursing infants receive less than 1.85% of the weight-adjusted maternal oral dose. Paracetamol is not contraindicated in lactating mothers based on current published data.

Studies show that caffeine is excreted into human breast milk and cases of irritability and poor sleeping in the infant have been reported. Caffeine in breast milk may potentially have a stimulating effect on the breast fed infant.

See references