Nearly one in five pregnant women still smoke in the third trimester of pregnancy. This is the highest rate in Europe. Smoking during pregnancy is an established risk factor for the unborn child: risk of ectopic pregnancy, intrauterine growth restriction and prematurity, risk of sudden infant death syndrome (increased two- to threefold), and risk of respiratory problems for the newborn. The risks increase with the frequency and duration of the mother's smoking during pregnancy.

Quitting smoking is essential to prevent the risks associated with tobacco use during pregnancy. The evidence of benefits for the child from pharmacotherapeutic interventions (nicotine replacement therapy) is insufficient. New treatment options must be explored to help pregnant women quit smoking.

Financial incentives are recognized as an effective means of motivating behavior change. It is about impacting the trade-off of quitting smoking. The trade-off consists of the benefits of quitting (improved health and reduced monetary costs because tobacco is no longer purchased) and the costs of quitting (suppressing the satisfaction and pleasure derived from smoking). One consortium member conducted a large clinical trial showing that a financial incentive is an effective intervention to help pregnant women who smoke to quit smoking.

Previous studies have shown that 70% of partners of women who use tobacco are themselves smokers. The partner's smoking is a risk factor for continued tobacco use during pregnancy and can be a source of passive smoking for the mother and child. Women who quit smoking before and after pregnancy are more often in relationships with nonsmoking partners than those who continue to smoke.

The investigator hypothesize that a financial incentive aimed at the partner's abstinence from tobacco will enhance the beneficial effects of the financial incentive on reducing or stopping tobacco use during pregnancy. The investigator also hypothesize that incentivizing the partner to stop smoking will help strengthen their engagement in family life.

Inclusion Criteria:

• Consent to participate in the study
• Agree to monthly prenatal follow-up at the maternity unit
• Understand French
• Are enrolled in health insurance or benefit from AME (Aide Médicale d'État)
• 18 years of age or older

Exclusion Criteria:

• Who do not wish to quit smoking
• Whose partner does not wish to quit smoking
• Who use electronic cigarettes in a complementary or exclusive manner (not applied to the partner) at inclusion
• Who will separate from the father of the unborn child and/or no longer cohabit with him
• Who will not be able to participate in the entirety of the study (e.g., planning to move after the birth of the child)
• Who do not wish to give birth in one of the study maternities.

Women who identify as women (with a uterus)