Behold a Baby, and Consider Heightened Sexual Conflict

A recent New York Times piece discussed the most common Internet searches associated with pregnancy in 20 countries. In almost every one of these countries—from India to South Africa to the U.S. to Mexico—sex was among the top five topics. Does this mean that pregnant women have unleashed their passions? Without concern over a new conception or menstruation, have pregnant women been released to new heights of sex and intimacy?

Although quantitative search data cannot unpack the meaning of these patterns, various lines of evidence suggest the kind of story line behind those search data. This is a compelling body of work that addresses “peripartum” (pregnancy and postpartum) impacts upon sexuality, both of a woman’s and a man’s.

From a life history standpoint, investment in a new life (e.g., gestation, nursing) can be viewed as a tradeoff between current and future reproduction. A woman’s physiology is oriented toward developing the fetus in the womb, to later possibly breastfeeding her child, and years and years of care. All of that investment may help launch her child to social success. However, that investment in the current reproductive output may come at some expense to conceiving another child. The energy used during pregnancy may leave a woman tired, with less concern over sex. Her body is more focused on increasing her fat reserves because nursing her future infant will be incredibly energetically demanding. More regular and intensive nursing of her infant can delay her resumption of cycles. This also postpones the rise of ovarian hormones such as estrogen and testosterone. A result is that sex after a baby may be more painful, in part because of reduced estrogen-facilitated vaginal lubrication.

The limited data on sexual behavior among humans and nonhuman primates during pregnancy and postpartum suggests several patterns. One is that sex during pregnancy is more common than during a phase of postpartum lactation, particularly when a female is not cycling. If capuchin monkeys in Costa Rica could use the Internet, they would probably be more likely to search for information about sex during pregnancy rather than postpartum since pregnant females are more sexually active than postpartum non-cycling females. Data from a good number of North American and European studies on sexuality during pregnancy and postpartum generally portray declining frequencies of sexual intercourse across pregnancy, and the lowest points for females tend to be in late pregnancy and an early postpartum phase. It is much easier for a woman and her partner(s) to negotiate sexual behavior while she is pregnant than when she has a one-month old infant in hand.

The thrust of the Internet search patterns concerning sex, I suspect, is women and men wondering what is safe for the fetus, and how to negotiate sexual behavior in the wake of changing life history priorities, physiology and motivations.

What about fathers? How does a partner’s pregnancy and becoming a father impact men’s sexual desire, other facets of their sexual function (such as sexual satisfaction), and measures of their sexual behavior? The impacts of pregnancy and postpartum care are less dramatic in men than women, and this includes impacts on paternal sexuality. A fraction of men report lower libido during a partner’s pregnancy, and in some men this has been shown to persist postpartum too. Because men’s sexual behavior often aligns with that of a regular partner (as in marriage), a man’s sex life becomes largely packaged with that of his pregnant or postpartum partner’s across these transitions. That means men also tend to experience marked declines in intercourse frequency during late pregnancy and postpartum. Changes in sexual positions and practices (e.g., reductions in oral sex) commonly apply to him and her. However, several studies in countries such as Germany found no change in men’s masturbation rates across a partner’s pregnancy and postpartum. In societies that allow men to marry polygynously, a pregnant and postpartum partner’s sex life tends to be more proscribed, which encourages a focus on her current reproduction while the man’s sexuality may be channeled toward other outlets such as a co-wife.

Because a father’s sexual desire is less impacted during a peripartum transition than a mother’s, and in ways that fit with sex differences in reproductive effort and life history theory, any sex differences in sexual desire tend to amplify during late pregnancy and early postpartum. Strangely, this context-specificity of sexual desire has received little attention. When Roy Baumeister and colleagues published a review of sex differences in human sex drive, they did not consider how the magnitude of the sex difference might fluctuate during a peripartum transition. In the two nationally representative probability studies of U.S. sexuality, neither considered pregnancy or parenthood as factors potentially accounting for variation in sexual behavior. Yet plenty of people are googling for information on such topics.

Masters and Johnson, in their classic book on the “Human Sexual Response” had considered what pregnancy and postpartum phases might do to individual’s sexual physiology, but also to partner dynamics. They wrote, “Sex weeks before and six weeks after delivery usually are proclaimed restricted periods by medical interdiction. Many male partners first break marital vows during this three-month period.” (p. 168). Far away from mid-20^th century St. Louis, Barry and Bonnie Hewlett noted that sex during pregnancy among the Aka and Ngandu of Central African Republic might be viewed as necessary work to spur a fetus’ continued growth. However, after birth, some young Aka hunter-gatherer men as well as most agriculturalist Ngandu men also stated that this would be a time when they would seek an additional sexual partner.

Behold a baby, and consider the heightened sexual conflict in sexual desire that may surround it. But like many things in life, good negotiation can go a long way to bridging the differences.