Safety has not been established during pregnancy.
-According to some authorities: Use is contraindicated.
-According to some authorities: Use should be avoided during the week before parturition.
-According to some authorities: This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.

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

Animal studies have not been reported. There are no controlled data in human pregnancy.

Oral chloramphenicol crosses the placenta. While there are no literature reports linking the use of this drug in pregnancy to birth defects, use late in pregnancy has been associated with adverse effects in the neonate (i.e., grey baby syndrome).

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.

See references

Milk levels are not enough to induce grey baby syndrome, but since drug-induced aplastic anemia is not dose-related, this might occur (but has not been reported). There is a theoretical risk of bone marrow depression, but this has not been reported.

Reported milk levels varied some, apparently due to use of older assay techniques in early studies.

In 10 breastfeeding women, peak milk levels were 1.7 to 2.8 mg/L during therapy with 250 mg orally 4 times a day and 3.6 to 6.1 mg/L during therapy with 500 mg orally 4 times a day.

A single 500 mg oral dose was administered to 4 women. Peak milk level averaged 3.24 mg/L (range: 2.5 to 4.5 mg/L) and occurred 2 hours after dosing; by 8 hours after dosing, milk level averaged 0.31 mg/L. In 5 other women administered 500 mg orally 3 times a day (at 7-hour intervals) for 2 days, breast milk drug levels were 1.72 and 0.66 mg/L at 24 and 48 hours after the first dose, respectively; the half-life in milk averaged 1.77 hours.

After a single 500 mg oral dose in 2 women, the drug was first measurable in milk 2 hours after dosing with a level of 3.3 mg/L; at 4 and 6 hours after dosing, milk levels averaged 4.1 mg/L at both times.

In 1 study, there were 50 breastfed infants whose mothers were administered 1 g/day (n=20), 2 g/day (n=20), or 3 g/day (n=10) orally, starting 2 to 12 days postpartum. All infants refused to suck and 50% to 60% fell asleep during nursing. Vomiting occurred after feeding in 10%, 25%, and 90% of infants with daily maternal doses of 1, 2, and 3 g, respectively. All infants had excessive intestinal gas and abdominal distention; severe problems occurred in 0.5%, 20%, and 100% of infants with daily maternal doses of 1, 2, and 3 g, respectively.

LactMed: An alternative agent is preferred, especially while breastfeeding newborn or preterm infants. If the mother must receive this drug during nursing, the infant should be monitored (gastrointestinal disturbances, adequacy of breastfeeding, complete blood count and differential); discontinuation of nursing may be preferred in some cases.
WHO: Use should be avoided if possible, especially in infants younger than 1 month; infants should be monitored for side effects (hemolysis, jaundice).
-According to some authorities: Use is contraindicated.
-According to some authorities: Use is not recommended.
-According to some authorities: A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Excreted into human milk: Yes

Comments:
-Adverse effects (e.g., falling asleep at the breast, excessive intestinal gas, vomiting) have been noted in nursing infants whose mothers were taking oral chloramphenicol.
-There is a theoretic risk of idiosyncratic bone marrow suppression and grey syndrome in the infant.
-Use of this drug during breastfeeding is considered to be of concern by the American Academy of Pediatrics; according to some experts, this drug should be avoided.

See references