Fertility decline in rural sub-Saharan Africa has lagged behind other developing countries. The gap in fertility preferences between men and women plays a pivotal role in determining household fertility and reproductive health outcomes, with men desiring more children and exerting more significant influence in household decision-making. This disparity becomes more pronounced in rural regions where patrilineal norms, especially those associated with land inheritance, remain prevalent. We estimate the effect of an informational family planning intervention on male and female fertility preferences in rural Tanzania. The experiment consisted of randomizing household consultations on modern contraception, with sessions conducted either jointly for husbands and wives or exclusively for wives in private. Surprisingly, husbands who engaged in joint consultations increased their desired additional number of children, and their wives mirrored this increase in fertility preferences. In contrast, women in private consultations reduced their additional desired number of children while their husbands’ preferences remained unchanged. We provide suggestive evidence that the unintended effects on fertility preferences might be motivated by land inheritance expectations, as our results are driven by households with firstborn daughters (rather than sons).