Love making at term hastens the onset of labor?.

Abstract


OBJECTIVE:

To determine whether sexual intercourse at term hastens the onset of labor and to observe its effect on cervical status.

METHODS:

Women with low-risk pregnancies at term were asked at each of their term prenatal visits whether they had engaged in penile-vaginal intercourse during the previous week. Delivery outcomes were compared between those women who were sexually active at term and those who were not. A Bishop score was assigned to each cervical examination at term, and the weekly results of the cervical examination were compared between women who were sexually active in the previous week and those who were not.

RESULTS:

Forty-seven (50.5%) of 93 women reported having had sexual intercourse at term. The gestational age at delivery of those women who were sexually active at term was greater than those who were not (39.9 weeks versus 39.3 weeks). There was no difference in Bishop score between women who had sex in the previous week and those who had not. After adjusting for the effect of time, those who were sexually active the previous week had Bishop scores that were, on average, lower by 0.26 compared with those who abstained.

CONCLUSION:

Sexual intercourse at term is not associated with ripening of the cervix and does not hasten labor.

Introduction

Many pregnant women (and some physicians) believe that sexual intercourse at term will hasten the onset of labor. One recent study showed that 73.6% of pregnant women were aware of this concept, and 46.1% believed it to be true. Several identified a physician or health care worker as the source of the information. The willingness to accept this belief is understandable, given that there is some biological plausibility regarding the effect of intercourse on initiating labor. Semen contains prostaglandins, and prostaglandin concentrations in the cervical mucus of pregnant women have been demonstrated to be 10- to 50-fold higher than normal 2–4 hours after intercourse. Sexual intercourse may also have an effect on uterine contractility.

Contraction monitoring of pregnant women during intercourse in late pregnancy has revealed increased uterine activity after coitus, although it is unclear from this study whether this was an effect of maternal or paternal orgasm. Maternal orgasm alone, achieved by genital manipulation without intercourse, has been associated with increased uterine contractions.

Despite the possibility of an effect on labor, there is little evidence to suggest that coitus can initiate labor. Sexual activity in low-risk pregnancies is not associated with preterm birth, premature rupture of membranes, or low birth weight. Although one report suggests an increased risk of preterm rupture of membranes after sexual activity, this association was not present in term pregnancies. There are few data available to adequately counsel pregnant women at term about the potential effect of coitus on labor and delivery.

The objective of this study was to determine whether women who are sexually active at term are more likely to enter labor than those women who are not. The study also investigates the effect of term intercourse on cervical change. A secondary objective was to provide data on the safety of engaging in sexual intercourse at term.

Provided that prostaglandins may be used as a cervical ripening agent, the study also examines the effect of term intercourse on cervical change on a weekly basis. The hypothesis would be that, even if labor does not ensue earlier after intercourse occurs, the cervix may become more favorable in the presence of seminal prostaglandins.

DISCUSSION

The results of this study indicate that there was no meaningful relationship between sexual intercourse at term and the onset of labor. In contrast, a prolongation of pregnancy in women who are sexually active in the final weeks of pregnancy was observed in this study. This prolongation of 4 days is not clinically significant. Because the variability in gestational age was small, however, the difference between groups achieves statistical significance. The finding that greater cervical change does not occur in sexually active women at term also supports the lack of an effect of sexual activity on inducing labor. Apparently, there is no relationship between coital frequency and onset of labor.

These findings agree with the results of a British retrospective study demonstrating an increased duration of gestation with increasing coital frequency at all gestational ages up through 37 weeks. Similarly, low-risk women delivering prematurely in another study were less likely to be sexually active than the full-term controls.

One possible explanation for these findings is that women may continue to be sexually active if they remain in a state of relative comfort. Women who are experiencing greater abdominal discomfort, pelvic pressure, or increased contractions are less likely to remain sexually active at term. Such symptoms might be markers for earlier delivery.

All of these studies examine sexual behavior in pregnancy retrospectively and thus are subject to several biases. There is only one prospective, randomized study in the literature that examined the effect of intercourse on initiating labor. Twenty-eight women at term were randomly assigned to have intercourse for three consecutive nights or abstain. There was no difference between the groups afterward in Bishop scores or number of women in labor. This study limits this intervention to a short course and does not describe the effect of preceding sexual activity.

The personal and highly variable nature of sexual behavior is such that it is not feasible to carry out a prospective study that randomly assigns subjects to a particular diet of sexual activity in pregnancy. Sexual activity may occur for a variety of reasons and in a variety of situations that make it very difficult to identify what confounding factors are present that influence the onset of labor. For example, sexual activity may or may not include breast stimulation, which has been demonstrated to have a positive effect on inducing labor. Because condom use was rare in the study population, the effect of paternal ejaculation could not be distinguished from the effect of intercourse itself. Assuming that penile-vaginal intercourse without a condom always involves the introduction of seminal fluid into the vagina, there are still several variables that may impact the effect on the cervix, including volume of ejaculate, concentration of prostaglandin within the ejaculate, or proximity of ejaculate to the cervical os. Likewise, different aspects of the maternal sexual response may impact the results, including degree of arousal and engorgement, presence of orgasm, and possibility of multiple orgasm. The present study did not elicit this information from its subjects; as such, it cannot address what effect the components of each sexual encounter might have on the onset of labor. Clearly, further research is needed to determine what role if any is played by each of these components.

By enrolling in this study, participants may have been subject to a suggestion bias, whereby they may have been inspired to try sexual activity to initiate labor when they might not otherwise have done so if the subject had not been discussed. Those subjects who had intercourse more frequently might then have wanted to shorten the duration of pregnancy for a multitude of other reasons. This may also explain why more elective inductions were performed for those patients who were sexually active because these inductions were generally initiated at the patient's request.

Beyond these inherent biases, the study has other shortcomings. Placing all patients with any sexual activity into a single group may not reflect differences between those with a single act of intercourse and those who regularly engage in intercourse. A larger study would be able to stratify this characteristic. Because the author was not usually present when the patient arrived at the hospital in labor, data were not collected regarding the presence or frequency of sexual activity in the period of time immediately before labor. This information might be more meaningful than data elicited the week before. Because each cervical examination was compared only with the sexual activity in the prior week, this measurement was still felt to provide meaningful data.

Regardless of the motivation to engage in sexual activity, this study has identified a larger proportion of patients at term having sex than in previous studies. Over half of the patients in this population reported sexual activity beyond 37 weeks, despite the large percentage of unmarried individuals. Obstetric caregivers should be aware of this behavior to better counsel their patients. The lack of condom use in this population might be understandable given the absence of a need for contraception, but the role of condoms in preventing sexually transmitted infections should be emphasized in high-risk populations.

Caregivers should take the initiative in talking with their patients about sexuality in pregnancy because it is clearly a concern of a significant proportion of their patients. From the data presented, this discussion should not lead patients to believe that sexual intercourse will initiate labor sooner. Although there does not appear to be any significant morbidity associated with sex at term in patients at low risk for complications, there are no data to support recommending sexual activity. Patients may continue to hear from relatives and other “old wives” that intercourse will hasten labor, but it should not be given credence by the medical community.