Association between cocaine abuse in pregnancy and placenta-associated syndromes using propensity score matching approach.

AIMS: We used propensity scores matching techniques to assess the association between maternal cocaine abuse in pregnancy and the occurrence of placenta-associated syndromes (PAS).

STUDY DESIGN: Mothers who abused cocaine (n=5026) were matched to controls (n=5026) from a sample of 1,693,197, unexposed mothers in Florida from 1998 to 2007. Cocaine abuse was identified using the ICD-9 principal and secondary diagnosis codes (304.2 for cocaine dependence and 305.6 for cocaine abuse). The outcome of interest, PAS, was identified as any indication in diagnosis field of ICD-9-CM codes for: placental abruption (641.2), oligohydramnios (658.0), placental infarction (656.7, 656.8, 656.9), gestational hypertension (642.3, 642.9), preeclampsia (642.4, 642.5, and 642.7) or eclampsia (642.6).

RESULTS: Nearly 6% of mothers in the study sample experienced a condition associated with PAS prior to matching. Women who abused cocaine were 58% more likely to have PAS when compared to women who did not (OR=1.48, 95% confidence interval: 1.33, 1.66). Women who abused cocaine were at elevated odds for placental abruption, placenta infarction and preeclampsia with the most pronounced odds noted for placental abruption (OR=2.79, 95% confidence interval: 2.19, 3.55).

CONCLUSIONS: These findings indicate that cocaine abuse during pregnancy is associated with more placenta-related disorders than previously reported.