While there is a physiological basis for the concern about preterm birth with sex in pregnancy, this risk has not been demonstrated in retrospective and prospective studies. In fact, in low-risk patients, sexual activity is typically associated with a decrease in preterm birth. In patients with a history of preterm birth, there is also no evidence that sexual activity increases the risk of preterm birth. Sexually transmitted infections (STIs) should be avoided in pregnancy due to the well-documented increased risk of preterm birth. Notably, sexual cohabitation for 12 months prior to conception (with maternal exposure to sperm) leads to a decrease in preeclampsia and likely to the risk of preterm birth.

Throughout the three trimesters of pregnancy, there is a remarkable adaptation of the whole body to accommodate the growing uterus and fetus, as well as upcoming labor and delivery. Most of these physiological changes gradually regress over the postpartum, returning to prepregnancy levels from a few weeks up to 6 months later. The changes that occur in pregnancy have an important impact on a woman’s sexual functioning (desire, arousal, orgasm, sexual satisfaction). Despite the implications of these physiological changes during pregnancy, which affect intimacy and sexual function, these are seldom discussed by health professionals and care providers. The adjustments and changes in different systems throughout the pregnancy are explained in this chapter, focusing on those with implications for sexual function and the mechanisms behind them.

Female engagement in oral sex, both receiving and performing, is a sexual behavior found throughout the animal kingdom, yet it remains an underdeveloped research area. Regardless, proximate and ultimate causes can explain engagement in oral sex. For instance, there have been various sociocultural impacts that have led to fluctuations in the performance frequency of oral sex over human history. In this chapter, we highlight the results of research on oral sex for women. First, cross-cultural and historical practices regarding oral sex are presented to explain various fluctuations in the behavior. We also examine cross-species examples of oral sex. Second, we present contemporary research on oral sex and aspects that impact its frequency, such as peer pressure, age, and myths regarding the behavior. Third, proximate mechanisms (sexual pleasure and partner satisfaction) for engagement in oral sex are discussed. Fourth, we describe six evolutionary perspectives on oral sex and introduce one additional theory—a sexual communal perspective that integrates other models. Lastly, we note limitations and future directions for studying women's engagement in oral sex.