Does sonographic determination of placental location predict fetal birth weight in diamniotic-dichorionic twins?

The effect of placental location identified before delivery on birthweight discordance among diamniotic-dichorionic twin pregnancies: a three-year retrospective cohort study

This retrospective cohort study aimed to investigate the effect of placental location on birthweight discordance among diamniotic-dichorionic twin pregnancies. Medical records and sonographic reports of 978 diamniotic-dichorionic twin pregnancies delivered at Foshan Maternal and Fetal Health Hospital were reviewed. Pregnancies with congenital malformation, intrauterine death or placenta previa were excluded. The placental location for each twin was determined by last sonographic examination before delivery, and the pregnancies were grouped by different versus same placental location in each pregnancy. Maternal and fetal characteristics were summarized. The primary outcome of interest was birthweight discordance (BWD) ≥20%, and secondary outcomes included small for gestational age (SGA) as a binary outcome and mean value and absolute difference in birthweight as continuous outcomes. Student’s t test and the chi-square test were used for univariate analyses, while multivariate regressions were used to adjust for confounders. General estimated equation (GEE) models were used to address the correlation between fetuses when assessing SGA. A total of 866 eligible subjects were included in the analysis. In total, 460 pregnancies had placentas with different locations, and 406 had placentas with same locations. The gestational age at delivery was slightly younger in the same placental location group than in the different placental location group (35.8 ± 0.1 vs. 36.1 ± 0.1 weeks, P = 0.067). Other maternal and fetal characteristics were comparable between the two study groups. There was no significant difference in BWD ≥20% (aOR = 1.06; 95% CI: 0.71–1.59) or SGA (aOR = 1.32; 95% CI: 0.76–2.28) between the same and different placental location groups. Neither the mean value nor the absolute difference in birth weight was associated with placental location combination (P = 0.478 and P = 0.162, respectively). In conclusion, discordant birthweight is not affected by same location of diamniotic-dichorionic placentas.

Neonatal morbidity and mortality among growth-discordant dichorionic twins, classified according to birth weight of the smaller twin: a population-based cohort study

Objective: To examine the outcomes among discordant dichorionic (DC) twins, where the smaller twin is small for gestational age (SGA) or non-SGA.Materials and methods: We used the national perinatal registry to compare the relationship between selected maternal characteristics (age, parity, body mass index, gestational diabetes, hypertensive disorders, and gestational age at delivery) and neonatal outcomes in discordant >25% DC twins. Chorionicity was established by standard ultrasound criteria and confirmed postpartum. The smaller of the twins was further classified as SGA or non-SGA. The neonatal outcomes included 5-min Apgar score <7, admission to neonatal intensive care unit, early neonatal death and neonatal morbidities.Results: We identified 377 pairs of DC discordant twins >25% born during the 15 years study period, 270 (71.6%) of which included an SGA smaller twin and 107 (28.4%) were non-SGA smaller twin. Maternal characteristics and neonatal morbidities were unrelated to the smaller discordant twin being SGA. A significantly increased incidence of stillbirth was found in the SGA group. Early neonatal deaths were only found in the SGA group.Conclusion: When the smaller twin is SGA, the growth discordant DC twin pair is associated with increased incidence of perinatal deaths. These appear unrelated to maternal characteristics and neonatal morbidity.

Nonpresenting Dichorionic Twins and Placental Vascular Malperfusion

OBJECTIVE

To explore the hypothesis that selective placental pathology affecting the nonpresenting twin is a significant contributory factor mediating the smaller size at birth of nonpresenting dichorionic twins.

METHODS

We conducted a retrospective cohort study of all dichorionic twin deliveries in a single tertiary center between 2002 and 2015 where by departmental policy, all placentas from multifetal gestations are routinely sent for pathologic examination. Maternal charts, neonatal charts, and pathology reports were reviewed. Placental abnormalities were classified into lesions associated with maternal vascular malperfusion, fetal vascular malperfusion, placental hemorrhage, and chronic villitis. Comparison of neonatal outcomes and placental abnormalities was made between all nonpresenting and all presenting twins as well as within twin pairs.

RESULTS

A total of 1,322 women with dichorionic twins were studied. Nonpresenting twins were smaller at birth compared with the presenting cotwin starting at 32 weeks of gestation (birth weight [±standard deviation] 2,224±666 g compared with 2,278±675 g, P=.036). Nonpresenting twins had smaller placentas (361±108 g compared with 492±129 g, P<.001) as early as 24 weeks of gestation. Nonpresenting twins had higher odds for any placental abnormality (adjusted odds ratio [OR] 1.91, 95% confidence interval [95% CI] 1.63-2.23), small placenta (adjusted OR 4.69, 95% CI 3.75-5.88), and maternal vascular malperfusion (OR 2.75, 95% CI 2.32-3.27) compared with their presenting cotwins. In nonpresenting twins, the presence of maternal vascular malperfusion pathology was associated with lower birth weight compared with their presenting cotwin during the third trimester.

CONCLUSION

The lower birth weight of nonpresenting fetuses in dichorionic twin pregnancies is correlated with a higher rate of placental maternal vascular malperfusion pathology.

Neonatal small-for-gestational age status as a favorable factor for the complete vaginal delivery of both fetuses in Japanese dichorionic twins

AIM

In singletons, neonatal small-for-gestational age (SGA) status is an unfavorable postpartum outcome leading to cesarean section (CS) and increasing the possibility of maternal operative complications. Perinatal characteristics of SGA newborns in dichorionic (DC) twins were investigated for the prognostic impact on their mothers.

METHODS

A retrospective study was performed from 2004 to 2009 on 329 DC twins with two live births. Neonates were classified as SGA if they weighed less than the 10th percentile at birth according to Japanese singleton norms. Statistical differences between DC twins delivering appropriate-for-gestational age (AGA)/AGA pairs (control group) and AGA/SGA, SGA/AGA or SGA/SGA pairs (the first/second twins) were analyzed.

RESULTS

The median (range) of the gestational ages at delivery for AGA/AGA, AGA/SGA, SGA/AGA and SGA/SGA pairs were 37.1 (27.1-40.3), 37.2 (29.0-40.9), 37.1 (28.1-40.7) and 37.3 (33.3-40.4) weeks, and the complete vaginal delivery rates of both fetuses were 66.2% (43/65), 84.8% (28/33), 82.4% (14/17) and 70.0% (7/10), respectively. Compared with AGA/AGA pairs, AGA/SGA pairs showed a higher incidence of spontaneous vaginal births of both fetuses (31.3% [26/83] vs 19.9% [37/186], OR 1.84, 95% CI 1.45-4.73) and a lower incidence of emergent CS (25.3% [21/83] vs 38.7% [72/186], OR 0.53, 95% CI 0.30-0.95).

CONCLUSION

The relatively small size of SGA fetuses allows both fetuses to remain inside the uterus for a longer time and to easily pass through the maternal parturient canal for complete vaginal delivery. Neonatal SGA status is a favorable factor for avoiding operative complications of CS and optimizing maternal perinatal outcomes.