According to this article, some women reduce their use of alcohol, cigarettes, and marijuana while pregnant. However, many continue to use at least sporadically, and a sizable number don't change their habits at all. The numbers:
* 77 percent of women cigarette smokers and 50 percent of the women who smoked marijuana used those substances at some time during pregnancy.
* 38 percent of women cigarette smokers and 24 percent of marijuana users reported using those substances throughout their pregnancies.
* While overall rates of cigarette and marijuana use and binge drinking for women declined during pregnancy, those rates began rising again during the first six months following the birth of a baby.
The study also found that fathers were not changing their habits appreciably. The explanation for this was that public service announcements and other information provided to prospective parents focused on the mother's use of these drugs, and did not speak to the behavior of the men. However, as the article notes, having another person in the house who is using a substance you already may crave will make quitting all that much harder.
The article suggests two strategies for combating this trend. First, there is an urging toward health care providers to talk with prospective parents about health care issues such as drug use even more, especially towards fathers who might traditionally be left out of that conversation. Second the authors suggest there needs to be a shift in the popular conventional wisdom regarding the use of drugs, especially marijuana, during pregnancy. "We also need to change the way society presently looks at the social norms of using these drugs. Right now there is little discussion about marijuana use during pregnancy, although it may be a relatively prevalent problem," according to Karl Hill, one of the authors of the study.
Of course you do everything you can, but this is a tough nut to crack. The optimist in me will look at the changing habits of smoking over the last few decades and believe this trend can also be reversed. However, this group has resisted the smoking trend (they are still smoking), so this are likely less amenable to change. In addition, several decades is a long time to shift something like this, because every baby born in the meantime by a couple who was using during the pregnancy is more susceptible to future problems, including the types of problems that perpetuate this problem (i.e. poor frustration tolerance, distractibility, etc.). Who knows? Maybe some other solution is out there, just waiting to be invented...