Weight gain patterns during twin gestation.

Twin pregnancy is a high-risk condition that mandates careful monitoring during the prenatal period. While assessment of weight gain is a routine practice, data are lacking on weight gain patterns associated with optimum outcome in this population. The recommended weight gain for singleton gestation is about 10.9 to 12.3 kg (24 to 27 lb) (1), although greater or lesser gains may be appropriate when prepregnancy weight is low or high (2-5). Even though it is reasonable to assume that multiple gestations are associated with greater weight gains than singleton pregnancies, the extent of the differences has not been carefully studied.

Leonard (6) has suggested that a weight gain between 18.2 and 36.4 kg (40 and 80 lb) is normal for twin pregnancy Campbell (7) reported that mean total weight gain in twin pregnancy at 36 weeks' gestation is 14.5 kg (32 lb). However, neither of those clinicians described their populations, so one must assume that the data derive from clinical experience with twin pregnancies, with outcome variables not carefully defined.

In the present study weight gain patterns in 217 multiple pregnancies were evaluated. In addition, effort was made to define a mean optimum weight gain on the basis of selected criteria for optimum outcome. Although data from an even larger population might be desirable for development of a valid weight gain chart for twin gestation, the curve generated from the present investigation represents a step in that direction.

Method

Data were collected from the medical records of women who delivered twins at Swedish Hospital Medical Center, Seattle, from June 1982 through December 1986. Subjects with problems that were unrelated to the pregnant state but that would affect maternal weight gain, infant birth weight, or risk for premature birth were excluded from the study Such complications included diabetes mellitus, major infections, organic heart disease, drug addiction, or accident during pregnancy Women younger than 18 years were also excluded. Information gathered included: age, ethnic background, insurance or other mode of payment, marital status, gravidity, parity self-reported prepregnancy weight, delivery weight, progressive weight gain, reported cigarette or alcohol use during pregnancy, measured height, and medical complications. (For cigarette and alcohol use, data were recorded as drinks per day or cigarettes smoked per day) Data collected from the infant's chart included: birth weight, birth length, head circumference at birth, sex, zygocity, gestational age by Dubowitz score, Apgar score at 5 minutes, and infant disposition at birth Neonatal Intensive Care Unit or Well Baby Nursery).

Prenatal weight gain was calculated by subtracting the reported prepregnancy weight from the measured weight at delivery or last prenatal visit within 1 week of delivery. To better describe weight gain relationships, subjects with recorded heights were grouped according to percent ideal body weight (IBW). This was determined using data from the National Center for Health Statistics (8). The subjects were classified as normal weight (90% to 120% IBW), underweight <90% IBW), and overweight (> 120% IBW). These designations are similar to ones used in other studies (3,9,10). "Optimum" outcome was defined …