The study compared 540 woman from Auckland, Hawaii, California, Oklahoma and Iowa - and highlighted widespread and heavy use of cannabis, tobacco, and alcohol among Kiwis.
The study was designed to measure the effects of prenatal exposure to the drug methamphetamine by studying addicts who were pregnant - but results from a control group of non-meth users found that use of other drugs among pregnant New Zealanders was startlingly higher.
The effects of such drugs - illicit and legal - on unborn children include miscarriages, low birth weights, mental and growth problems.
The results, submitted for publication in the Journal of Drug and Alcohol Dependence, showed New Zealand women not only used more drugs than the US mothers, but used them in larger amounts.
General cannabis use was five times greater, alcohol was four times greater, and tobacco use was double.
Heavy use, involving more than half a joint, more than 15ml of alcohol and more than 10 cigarettes daily, was again extreme.
Heavy cannabis use was eight times greater in the New Zealand group, and while only meth-using US mothers drank alcohol heavily, 10% of non-meth users in New Zealanders hit the bottle.
University of Auckland senior lecturer Dr Trecia Wouldes, who directed research in New Zealand, said rates of mental illness and cases of sexual and physical abuse were also over-represented among Kiwis.
Alcohol Healthwatch health promotion adviser and Fetal Alcohol Network co-ordinator Christine Rogan said the findings did not come as a surprise.
"We know women are drinking more alcohol more often and more than in other countries," she said.
"People who smoke often drink and people who use other drugs often drink, so there is usually alcohol in the mix."
Ms Rogan said surveys done by the group showed a social acceptance of drinking while pregnant.
"I do get concerned as to where women may be getting their ideas about alcohol and other drugs during pregnancy. That is a great deal of concern for us because we know the effects are very real."
Children's Commissioner Russell Wills said the study raised questions for the health of children.
"The key findings in this study are the very strong prevalence of mental illness, sexual and physical abuse and methamphetamine and other drug use in New Zealand women, even more in New Zealand than elsewhere.
"The key issue is of course the effect of that mother's use on her children."
He said pediatricians were seeing the effects of drug use on children daily, and more thorough medical checks were needed - an issue addressed in the Green Paper on Vulnerable Children.
