Maternal mortality and drug use during pregnancy; national data for England (2002-2014)

Objectives: Drug dependence during pregnancy is indicative of future adversity for the mother and her child. We aimed to investigate neonatal abstinence syndrome (NAS) as a marker of drug-use in pregnancy and to compare... [ view full abstract ]

Objectives:

Drug dependence during pregnancy is indicative of future adversity for the mother and her child. We aimed to investigate neonatal abstinence syndrome (NAS) as a marker of drug-use in pregnancy and to compare maternal all-cause mortality relative to women without a NAS-pregnancy.

Methods:

De-identified Hospital Episodes Statistics (HES) inpatient data including hospital, GP practice, maternal age and birthweight were used for deterministic and probabilistic linkage of mothers and babies born in England between 1^st April 2002 and 31^st March 2014. Women who used drugs during pregnancy were identified using information from the baby’s record indicating NAS within a month of birth. All remaining mothers formed the comparison cohort. Deaths were identified from linked national mortality data. A single index birth was selected at random for each women, with the delivery date marking the start of follow-up. The association between drug use in pregnancy and the rate of mortality was modelled using Poisson regression.

Results:

The study population comprised 14,436 women with a NAS baby and 4,547,929 women without a NAS baby, corresponding to over 96% of all live births in England. On average, mothers of a NAS baby were younger at the time of delivery than those without a NAS baby (median age 28 years (IQR; 24.1-32.6) versus 30 years (IQR; 25.3-34.3), p<0.001). Ten-year mortality was 4.02 (3.63-4.46) per 1000 person years amongst mothers with a NAS baby and 0.37 (0.36-0.37) per 1000 person years for mothers without a NAS baby, yielding a crude incident rate ratio of 10.9 (95% CI 9.85-12.2).

Conclusions:

Women giving birth to infants with NAS are a population at high risk of premature mortality, and public health programs should target both infants and mothers to reduce the risk of adversity faced by these children.