Triplets are not so rare any more

Pregnancy-induced hypertension and infant mortality in triplets

OBJECTIVE

To assess the effects of pregnancy-induced hypertension on infant mortality in triplets stratified by gestational age at birth.

METHODS

A retrospective cohort study was conducted using the linked 1995-2000 US birth/infant death database. Generalized estimating equations were used to evaluate the observed association.

RESULTS

Pregnancy-induced hypertension was associated with lesser neonatal mortality (odds ration [OR]: 0.34, 95% CI: 0.21, 0.54), postneonatal mortality (OR: 0.54, 95% CI: 0.30, 0.99) and infant mortality (OR, 0.37, 95% CI: 0.25, 0.55) in triplets. It was also associated with a decreased risk of neonatal death (OR, 0.38; 95% CI, 0.21-0.67), postneonatal death (OR, 0.45; 95% CI, 0.21-0.97), and infant death (OR, 0.39; 95% CI, 0.24-0.64) in early preterm triplets, whereas the association was not significant in late preterm or in full-term triplets.

CONCLUSION

Pregnancy-induced hypertension is associated with a decreased risk of infant mortality in triplets. This effect varies with gestational age at birth.

Maternal physiology and complications of multiple pregnancy

Approximately 1% to 3% of all pregnancies in the United States are multiple gestations. The vast majority (97-98%) are twin pregnancies. Multiple pregnancies constitute significant risk to both mother and fetuses. Antepartum complications-including preterm labor, preterm premature rupture of the membranes, intrauterine growth restriction, intrauterine fetal demise, gestational diabetes, and preeclampsia-develop in over 80% of multiple pregnancies as compared with approximately 25% of singleton gestations. This article reviews in detail the maternal physiologic adaptations required to support a multiple pregnancy and the maternal complications that develop when these systems fail or are overwhelmed.

Cervical length in the early second trimester for detection of triplet pregnancies at risk for preterm birth

OBJECTIVE

Preterm triplet delivery is common and has a tremendous impact on neonatal mortality and morbidity. We aimed at assessing early second-trimester cervical length as a means of detecting triplet pregnancies at risk for preterm birth.

METHODS

Cervical length was measured in triplet pregnancies during weeks 14 to 20. Cervical length of less than 25 mm was used as a cutoff to divide individuals into 2 groups. Perinatal outcome parameters were compared between the 2 groups and included gestational age at delivery, birth weights, and neonatal intensive care unit admission rates. Sensitivity, specificity, and positive and negative predictive values were calculated for cervical length as a screening method for preterm birth.

RESULTS

We evaluated 36 triplets during weeks 14 to 20. Cervical length of less than 25 mm was measured in 14 (group I), 12 of which were delivered before 32 weeks (mean +/- SD, 28.4 +/- 3.1 weeks). Four of 22 women with cervical length of greater than 25 mm (group II) had delivery before 32 weeks (mean, 30.1 +/- 1.8 weeks). The mean gestational age at delivery for all parturients from group II was 33.1 +/- 2.1 weeks (P < .05). Group I neonates had lower birth weights (972 versus 1889 g; P < .001) and higher rates of low 5-minute Apgar scores and neonatal intensive care unit admissions compared with group II neonates. The sensitivity of a shorter cervix as a predictor of preterm labor was 75%, with specificity of 90%, a positive predictive value of 83%, and a negative predictive value of 81%.

CONCLUSIONS

Cervical length of less than 25 mm at 14 to 20 weeks' gestation is associated with preterm delivery and adverse perinatal outcome in triplet pregnancies.

Ultrasonographic assessment of cervical length in triplet pregnancies

OBJECTIVE

Our goal was to evaluate the utility of ultrasonographic assessment of cervical length in the management of triplet pregnancies and to compare these measurements with previously reported data for singleton pregnancies.

STUDY DESIGN

The maternal records for all triplet pregnancies managed at the Mayo Medical Center from January 1993-January 1998 were reviewed. Cervical length assessment was undertaken at regular intervals during each pregnancy according to an established real-time transperineal ultrasonographic technique. Presence or absence of cervical funneling was noted at the time of the examination. Obstetric management and outcome data were assessed.

RESULTS

Thirty-two triplet pregnancies were managed at our institution between January 1993 and January 1998. Average duration of pregnancy (+/-SD) was 32.4 +/- 2.3 weeks. Progressive cervical shortening was noted with advancing gestational age; average cervical lengths (+/-SD) were 42.0 +/- 5.0 mm at 10 weeks, 37.0 +/- 8.0 mm at 20 weeks, 26.0 +/- 10.0 mm at 25 weeks, and 21.0 +/- 7.0 mm at 30 weeks. Comparison of triplet cervical length measurements with reported data from singleton pregnancies revealed a significant difference between the singleton and triplet data, respectively, at both 24 weeks (35.2 +/- 8.3 mm vs 25.0 +/- 8.0 mm, P <.001) and 28 weeks (33.7 +/- 8.5 mm vs 28.0 +/- 11.0 mm, P <.005). Cervical funneling was noted in 3 women with an average of 27 days from onset to delivery.

CONCLUSIONS

Ultrasonographic assessment of cervical length is a useful adjuvant in the management of the triplet gestation. Triplet cervical length measurements are significantly different from those reported for gestational age-matched singleton pregnancies. Premature cervical shortening and the presence of cervical funneling are harbingers of premature delivery and should necessitate obstetric intervention.

Fetal growth in multifetal gestation

Multiple gestations present a significant increase in fetal growth abnormalities in direct relationship to the number of fetuses present. Various definitions of birth weight discordancy exist (> or = 15%-40%). When first trimester discordancy in CRL or gestational sac diameter or early second trimester discordancies of BPD, HC, AC, or femur length are detected, genetic counseling and further work-up, including chromosomal analysis, should be considered. AC and SEFW are the best sonographic predictors of second and third trimester growth discordancy of twins. Discordant Doppler velocimetry of the umbilical arteries enhances ultrasonographic diagnosis of twin discordancy. Karyotyping also should be considered on second or third trimester diagnosis of growth discordancy. Twin-twin transfusion should be considered when growth discordancy is diagnosed in monochorionic gestations. Concordant twins with appropriate-for-gestational-age growth parameters should be followed with repeated sonographic assessment of fetal growth at approximately 4-week intervals. Discordant twins should be followed by repeat sonographic assessment of fetal growth at closer intervals, most probably every 2 weeks. Surviving singleton fetuses, after spontaneous fetal death of a twin at > 16 weeks of gestation, should be followed with antepartum surveillance similar to that of discordant twins. In rare cases of extremely premature twins with discordant growth and deteriorating fetal well-being of the growth-restricted twin, conservative management should be considered in favor of the normally grown fetus.

Assisted reproductive technologies: estimates of their contribution to multiple births and newborn hospital days in the United States

OBJECTIVE

Estimate the contribution of assisted reproductive technology (ART) in the United States to multiple gestation births and newborn hospital days.

DESIGN

Analysis of successful ART conceptions occurring during 1990 to 1991 compared with vital statistics. Newborn hospital days are estimated from the 1990 National Hospital Discharge Survey.

SETTING

The American Fertility Society and the Society for Assisted Reproductive Technology registry.

PATIENTS

Infants delivered from ART.

INTERVENTIONS

Assisted reproductive technology.

MAIN OUTCOME MEASURES

Number of multiple gestation infants and newborn hospital days.

RESULTS

Approximately 12,327 live-born infants were delivered from ART conceptions during 1990 to 1991, representing 22.2% of all live-born triplet, 17.3% of quadruplet, and 11.4% of quintuplet infants born in the United States. The number of newborn hospital days attributed to ART infants was 87,135 days. Between the periods 1972 through 1974 and 1990 through 1991, the rate of triplet and higher order multiple gestation infants per 100,000 white live births increased by 191%, with 38% due to ART conceptions and 30% to increased childbearing among older women.

CONCLUSIONS

Assisted reproductive technology contributed 22% of U.S. triplet and higher order multiple births during 1990 to 1991.

Sex ratio in triplets

Since the introduction of different ovulation induction regimens the incidence of triplet pregnancies increased from a spontaneous rate of about 1:10,000 to the frequency of nearly 1:1000. Sex ratio of trigemini and male/female proportion of the three newborns within the same triplet set is the amazing issue that we attempted to elucidate in the present study. Data on 36 women with triplet pregnancies delivered in our hospital and information regarding 2717 triplet pregnancies reported by 16 relevant papers were included in this study. 36 women delivered 63 (58%) male and 45 (42%) female babies. Triplet sets of same gender comprised 33% of all trigemini. Sex ratios (male/female) for the spontaneous, menotropin and clomiphene group were 2.00, 1.57 and 0.94 respectively. Homogenous male/female set ratio was 5.0, 2.0 and 0.5 in menotropin, spontaneous and clomiphene groups respectively. As the percentage of ovulation induction triplet pregnancies increased constantly from 0% to 100%, a decline in the fraction of homogenous gender triplet sets was observed--from 73% to 23%. It may be concluded that sex ratio in triplet newborns is divergent according to different publications with most of the authors reporting a male/female ratio of less than 1.00. Ovulation induction results in a lower proportion of homogenous sex triplets sets. Superovulation by menotropins cause a higher percentage of male triplet newborns when compared to ovulation induction by clomiphene.