OBJECTIVE

To investigate the usefulness of the milk-to-plasma (M/P) ratio for assessing the risks for the breastfed infant associated with the maternal use of SSRIs.

DATA SOURCES

Medline, Toxnet, Embase, Current Contents, and PsycInfo indexed articles from 1980 to September 2006.

STUDY SELECTION AND DATA EXTRACTION

All studies reporting the M/P ratio in mothers taking SSRIs while breastfeeding or studies which such an information could be calculated from data reported in the article.

DATA SYNTHESIS

Higher M/P ratios were rarely associated with a clinically significant impact on the babies during the early phases of breastfeeding.

CONCLUSIONS

So far no evidence-based information seems to support the hypothesis that SSRIs characterized by a M/P ratio <1.0 should be preferred. Hence, physicians should consider different parameters when attempting to choose the safest SSRI for the breastfeeding woman. These parameters might be represented by the number of well-documented published adverse event reports and the tendency of each SSRI of inducing in the infants serum concentrations that are elevated above 10% of average maternal serum levels. In any case, if the mother wishes to breastfeed her infant while taking a SSRI, the baby should be closely monitored in order to promptly detect any iatrogenic event.