Among a diverse cohort of women enrolled in early pregnancy, periconceptional substance use demonstrated increased odds of unfavorable pregnancy contexts. Tobacco use was associated with increased odds of undesired or unsure pregnancy, and unhappiness or neutrality regarding the pregnancy, but was not associated with pregnancy intention, wantedness, planning, or timing. Alcohol use was associated with increased odds of pregnancy described as unintended or intentions changing, unwanted or mixed feelings, and unplanned or ambivalent, but was not associated with pregnancy planning, or desirability. Marijuana use did not show a significant association with any pregnancy context, and periconceptional substance use was not associated with pregnancies that were unplanned or ambivalent, or that occurred at the wrong or not quite right time.

Previous research has demonstrated an increased risk of alcohol use and unintended pregnancy,^11,26,27 although alcohol exposure is often assessed as patterns of heavy or binge drinking.^11,27 Studies have also reported an association between preconception and prenatal smoking and unwanted pregnancy^15,28; however, we observed no association with tobacco smoking and unwanted pregnancy but rather an increased likelihood of undesired or ambivalent pregnancy, and unhappiness with pregnancy news among women smoking tobacco during the periconceptional period.

Our robust analysis of multiple periconception substances and unique measures of pregnancy context in early pregnancy improves upon the current literature and illustrates the complexity of these relationships, which has important public health implications. For example, despite frequent public health focus on unintended pregnancy and substance use,^9–11 we demonstrate substance use was also associated with unwanted, undesired, and unhappy pregnancies. Public health efforts focused solely on pregnancy intention would potentially miss these other important pregnancy contexts, especially pregnancy contexts that reflect women's perspectives about the pregnancy after its diagnosis (desirability and happiness).

Our study improves upon earlier studies that are limited by potential misclassification of pregnancy intention based on complicated algorithms,^13,16 utilize national surveys^11,13,16 with retrospective assessments of pregnancy context and substance exposure that may be subject to recall bias,^11,14,15,26 and lack robust adjustment for potential confounders.¹⁰ In addition, our study is strengthened by enrolling women early in gestation; assessing substance exposure during the 3 months before enrollment (prospective to pregnancy outcome); directly assessing unique pregnancy contexts beyond intention, thus minimizing potential recall bias; and adjustment for multiple covariates in statistical analysis.

After adjustment for potential confounders including history of depression and/or anxiety, most significant substance use risk estimates were attenuated, demonstrating the importance of comprehensive multivariable modeling that includes evaluating history of depression and/or anxiety. Finally, we recruited women presenting for pregnancy testing, inclusive of all pregnancy outcomes including induced abortion, thus enhancing generalizability of our findings compared with studies frequently restricted to live births only.^11,13,16,26

Another strength of our study is its potential external generalizability. Our cohort is diverse in participant characteristics including race-ethnicity, marital status, education, and language. Research among a sociodemographically diverse population provides opportunities to better understand potential health disparities.

Periconceptional substance use in this study is similar to or above national estimates.²⁹ Specifically, reported alcohol use (54%) is consistent with previous research among reproductive aged women,^21,22,29 whereas tobacco and marijuana use in our study (31% and 21%, respectively) are above estimates among U.S. reproductive-aged women,²¹ suggesting reporting bias may be minimal. Notably, marijuana use is within estimates of use among younger urban populations (15%–28%).³⁰ Illicit substance use in our study, including marijuana (21%), cocaine (<1%), inhalants (<1%), and opioids (1.6%), is collectively higher (22.8%) than composite illicit drug use among pregnant (5.4%) and nonpregnant (11.4%) U.S. women of age 15–44 years,²⁹ and greater than previously reported periconceptional illicit substance use.³¹

Several study limitations are important to acknowledge. We did not assess income or recent contraception use, which may be important potential confounders. Our relatively small sample limits further stratification of substance exposure, and we are limited in our assessment of high levels of substance exposure. Specific substance measures, such as alcohol frequency, are limited in that they may not fully capture the scope of substance use and behavior. Further research delineating patterns of substance use (e.g., binge drinking) and higher sustained levels of substance use (e.g., chronic heavy drinking) and unfavorable pregnancy contexts would be informative.

In addition, few women in our study report using other illicit substances, including opioids; these substances are analyzed as a composite measure, precluding evaluation of individual illicit substances, or differentiation between illicit versus medically prescribed substances. Although self-reported substance use is subject to recall and social desirability bias, periconceptional exposure is assessed early in pregnancy among women averaging 7.5 weeks' gestation (range 3.7–18.7 weeks). Although exposure during the “past 3 months” may vary and encompass pre- and postconceptional period for most participants, methodological consistency was applied assessing exposure within 3 months before enrollment and pregnancy diagnosis, thus minimizing bias.

Further research is warranted identifying detailed substance exposure during the specific immediate preconception period as well as postconception period before pregnancy recognition, compared with after pregnancy recognition when behavior is often modified. Biomarkers of exposure were not collected for our analysis, which would increase precision of exposure assessment. In addition, although underreporting may threaten exposure assessment, acceptable agreement between self-reported substance use and toxicology results has been reported.³²

Our study demonstrates associations between periconceptional substance exposure and unique measures of pregnancy context among a diverse cohort of pregnant women. These findings support the need for more nuanced public health interventions that improve upon overly cautious and potentially impractical advice to all reproductive-aged women to avoid substances in case they get pregnant.^33,34 Instead, public health efforts that support women's “reproductive life planning” and encourage patient-centered assessments⁶ regarding potential pregnancy contexts, identify those at risk of unfavorable pregnancy contexts (e.g., unintended, unwanted, and undesired), and facilitate contraceptive access for those who want to avoid pregnancy may be more beneficial.

More specifically, our finding that periconceptional alcohol use was associated with increased odds of unintended or ambivalent pregnancy and unwanted or mixed feelings regarding pregnancy provides potential opportunities for decreasing negative birth outcomes associated with alcohol-exposed pregnancies. Furthermore, enhancement of preconception education and delivery of evidence-based information are needed, along with interventions to optimize preconception health.³⁵

Specific interventions to address preconceptional alcohol and tobacco use and effective contraception for those at risk of unintended pregnancy have been demonstrated²⁴ and may be an important step to address the increased risk of unfavorable pregnancy context measures we observe among women with periconceptional substance use. For example, the CHOICES Plus trial demonstrated a preconception intervention reduced the risk of alcohol- and tobacco-exposed pregnancies within primary health care settings,²⁴ and future efforts integrating similar approaches within reproductive health care and family planning settings should be evaluated.

Notably, our findings also reinforce growing literature that asserts pregnancy planning and intention may not have relevance for some women,^5,18 and warrant further assessment of improved measures regarding pregnancy contexts,^5,17–20 including how, when, and where these expanded context measures can be best used in clinical practice.

Our study highlights important pregnancy context measures beyond the construct of intention, and demonstrates opportunities to enhance education regarding contraception, substance use, and preconception health among reproductive-age women, especially those with the potential for unintended, unwanted, undesired, or unhappy pregnancies. These findings underscore the potential for increased contraceptive access as a public health primary prevention strategy for substance use in pregnancy, particularly for women at risk for unfavorable pregnancy contexts.