Multiple Pregnancy Clinical Findings

With the ready availability of ultrasound, fewer than 10% of twin gestations are undiagnosed before labor and delivery. Early diagnosis facilitates appropriate prenatal care.

A. Symptoms and Signs

All of the common annoyances of pregnancy are more troublesome in multiple pregnancy. The effects of multiple pregnancy on the patient include earlier and more severe pressure in the pelvis, nausea, backache, varicosities, constipation, hemorrhoids, abdominal distention, and difficulty in breathing. A "large pregnancy" may be indicative of twinning (distended uterus).

Fetal activity is greater and more persistent in twinning than in singleton pregnancy. The median weight of twins at birth is just over 2270 g in the United States. Male infants weigh slightly more than females.

Considering the possibility of multiple pregnancy is essential to early diagnosis. If one assumes that all pregnancies are multiple until proved otherwise, physical examination alone will identify most cases of twinning before the second trimester. Indeed, diagnosis of twinning is possible in over 75% of cases by physical examination. The following signs should alert the physician to the possibility or definite presence of multiple pregnancy:

(1) Uterus larger than expected (> 4 cm) for dates.

(2) Excessive maternal weight gain that is not explained by edema or obesity.

(3) Polyhydramnios, manifested by uterine size out of proportion to the calculated duration of gestation, is almost 10 times more common in multiple pregnancy.

(4) History of assisted reproduction.

(5) Elevated MSAFP values (see Laboratory Findings, below).

(6) Outline or ballottement of more than one fetus.

(7) Multiplicity of small parts.

(8) Simultaneous recording of different fetal heart rates, each asynchronous with the mother's pulse and with each other and varying by at least 8 beats per minute. (The fetal heart rate may be accelerated by pressure or displacement.)

(9) Palpation of one or more fetuses in the fundus after delivery of one infant.

Some of the common complications in early pregnancy may also occur as a result of multiple gestation. For example, maternal bleeding in the first trimester can indicate threatened or spontaneous abortion; however, the dead fetus may be one of twins, as demonstrated by real-time ultrasonography (one anechoic or hypoechoic amniotic sac and one normal sac). In the second and third trimester, the demise of one fetus in a multiple gestation may trigger disseminated intravascular coagulation ("dead fetus syndrome"), just as a singleton intrauterine demise might. This generally becomes a problem only 3 weeks or more after fetal demise. Preeclampsia-eclampsia is a common complication of multiple pregnancy.