Did low birthweight among US blacks really increase?

The low birthweight (LBW) rate among reported United States non-White births increased 32 per cent from 1950 to 1967. States with large increments in non-White LBW rates over the period 1950-67 ("rising LBW states") were compared to states with more stable LBW rates. Paradoxically, states with the most deterioration in LBW rates had the most improvement in LBW risk factors (low income, mothers under age 20 or over age 35, birth order over four). In 1950, at least 9.7 per cent of non-White births in rising LBW states went unreported, and underreporting was biased, with out-of-hospital LBW births who die young least likely to be reported. From 1950 to 1967, non-White out-of-hospital births for the US declined from 42 per cent to 7 per cent, and yearly values for per cent of non-White births in hospital and LBW rates were highly correlated (r = .98). These data suggest that the observed rise in non-White LBW rates from 1950 to 1967 was due in large part to systematic underreporting of LBW births among non-White out-of-hospital deliveries in the 1950s. This underreporting essentially ceased when hospital delivery for non-Whites became nearly universal in the late 1950s and 1960s.