A 30-year-old G6P2A4L1 is referred by her primary care provider to your high-risk obstetrics clinic for preconception counseling after a pregnancy loss at 21+4 weeks’ gestation last year, shortly after incidental transvaginal cervical shortening was noted at second-trimester fetal morphology survey. After an uncomplicated first pregnancy and term delivery, she experienced four consecutive first-trimester losses for which comprehensive investigations were unremarkable.

Spontaneous preterm birth (PTB) refers to a delivery that occurs between weeks 20 and 37 of pregnancy, due to preterm labor, preterm prelabor rupture of membranes. and short cervical length at mid-trimester. The three most common risk factors for PTB are (1) prior history of preterm delivery, (2) twin pregnancy, and (3) short cervix at mid-trimester ultrasound. Several studies have demonstrated that short cervical length is the most powerful predictor for PTB in the index pregnancy for both singleton and twin pregnancies. A short cervical length means the measured length of the cervix is shorter than expected for the current gestational age, with a cutoff value between 20 and 25 mm. Sexual intercourse by itself has not been demonstrated to be a clear risk factor for PTB. Thus, abstinence after pregnancy has been achieved has no role in strategies for prevention of PTB. Also, most sexual positions and noncoital activities (e.g. oral sex, masturbation) during late pregnancy are not clearly associated with adverse pregnancy outcomes. There is no strong evidence that sexual activity affects the risk of PTB or onset of labor in healthy individuals. Pelvic rest may be recommended in selected cases, such as patients with a very short cervix or bulging membranes.

Twin and triplet pregnancies have been associated with an increased risk for adverse maternal and neonatal outcomes. This chapter discusses select issues about sexual activity and twin pregnancy, especially with relation to preterm birth (PTB) and shortened cervix, two major concerns in this population. Two studies addressed the association of sexual activity with PTB in twin pregnancies. Overall, these studies do not support a relationship between sexual behavior and PTB in uncomplicated twin pregnancies. Unanswered questions still abound regarding twin gestations at higher risk of PTB, the effects of prostaglandins in semen on cervical length, the intensity of uterine contractions with orgasm on a compromised cervix, and sexual activity in the case of cervical cerclage. We suggest that sexual activity of any type should not be discouraged in twin gestations without other obstetric risk factors such as short cervix. Recommendations should be individualized bearing in mind patient history, comorbidities, and emotional needs.