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Title: The Effect of the Timing and Frequency of Marijuana Use on Fetal Growth Based on Sibling Birth Data
Resulting in 1 citation.
1. Rosenzweig, Mark R.
Wolpin, Kenneth I.
The Effect of the Timing and Frequency of Marijuana Use on Fetal Growth Based on Sibling Birth Data
Working Paper, University of Minnesota, Minneapolis, 1990
Cohort(s): Children of the NLSY79, NLSY79
Publisher: Author
Keyword(s): Alcohol Use; Birthweight; Cigarette Use (see Smoking); Deviance; Drug Use; Pre-natal Care/Exposure; Pre/post Natal Behavior; Pre/post Natal Health Care; Pregnancy and Pregnancy Outcomes; Siblings; Sons; Substance Use

Permission to reprint the abstract has not been received from the publisher.

A sample of 5669 births obtained from the NLSY is studied to investigate the effects of marijuana usage on fetal growth and the sensitivity of findings to the existence of both measured confounding risk factors associated with pregnancies and mothers and unmeasured risk factors characterizing mothers. In the bivariate relationships, infants born to women who smoked marijuana every month of the first trimester weighed 6.7 ounces less than women who did not smoke marijuana in the first trimester. Introducing controls for a large number of measured confounding risk factors identified in prior studies reduces the marijuana effect to 3.3 ounces. However, controlling in addition for all unmeasured attributes of the mother that are invariant across births using information on sibling births increases the estimated impact of marijuana use net of measured risk factors to 5.1 ounces, a value which is 52 percent higher than the standard multiple regression estimate. Further, the estimated marijuana effect obtained from this measure of use, which takes into account frequency and timing, is more than three times as large as the effect based only on a measure of ever-use in the first six months of pregnancy. The authors conclude that it is important to take into account unmeasured risk factors characterizing the mothers of infants in estimating the effects of substance use on fetal growth. Lack of controls for mother characteristics appear to lead to underestimates of the impact on fetal growth of the use of marijuana early into a pregnancy.
Bibliography Citation
Rosenzweig, Mark R. and Kenneth I. Wolpin. "The Effect of the Timing and Frequency of Marijuana Use on Fetal Growth Based on Sibling Birth Data." Working Paper, University of Minnesota, Minneapolis, 1990.