Журнал «Здоровье ребенка» 4 (47) 2013

The majority of scientists consider that an increase in the number of multiple pregnancies can be caused by the mother’s age over 35 years, extensive administration of therapeutic measures aimed at stimulation of ovulation and employment of assisted reproductive technologies [1]. This increase in the number of multiple pregnancies has been also observed in Ukraine [2,3]. Multiple pregnancies, especially in case of monochorionic twins, are known to result in a condition when the babies’ body mass significantly differs. Thus, some scientists suggest that fetal body mass discordance is a difference in body mass comprising more than 10 %, other scientists suggest that it is a difference in body mass more than 20% [4,5,6]. Discordance is a significant risk factor of miscarriages, premature labor, abnormal fetus development and high perinatal mortality rate [7,5]. However this supposition is denied by other authors who suggest that discordance does not have any influence on perinatal mortality [8]. Unfortunately, we have not obtained information concerning discordance and peculiarities of perinatal period course in bichorionic biamniotic twins.

Materials and methods of the research. The research included 26 women with multiple pregnancies who have been observed since the 32^nd week of pregnancy and their 52 infants. The research has made it possible to analyze peculiarities of ante-, intra- and early neonatal periods, anthropometric data of the newborns. Bichorionic, biamniotic twins were considered to be the inclusion criterion. The control group included 27 women with singlet pregnancy who have been observed since 32^nd week and their 27 newborns. A difference in fetal body mas more than 10% was considered to be discordance [4]. Umbilical bloodstream analysis was carried out at the 34^th week of gestation with the assessment of maximum bloodstream velocity (Vmax), minimum bloodstream velocity (Vmin), index of resistance (IR) and systole/diastole ratio (S/D) using Philips HD7 XE unit (Italy). To compare sample ratio we used angular transformation method with F-test; to compare indices with non-Gaussian distribution we used median (Me) and quartile values (Uq; Lq) and Mann-Whitney test (MW). Statistically significant discrepancy was considered in р<0,05.

Results and their discussion. Prospective observation of 26 women with twins and 27 women with singlet pregnancies allowed to determine the rate of premature labor in multiple pregnancy, which in this cohort of observation comprised 38,4 % (р=0,0012). At that, premature labor occurred in the terms close to physiological. In such a way, value of 37 (36;38) weeks was considered median and quartile range of gestation age in multiple pregnancies, and 39(38;40) weeks in singlet pregnancies. Thus, “near term infants” are more frequently born in multiple pregnancies. Pregnancy balance analysis has not determined significant discrepancies between multiple and singlet pregnancies. In such a way, first pregnancy was observed in 7(26,9±8,6 %) of women with multiple pregnancies and in 10(37±9,2%) in singlet pregnancies (р=0,4392); second pregnancy in 13(50±9,8%) and in 10(37±9,2%) correspondingly (р=0,3443); third pregnancy in 6(23±8,2%) and in 3(11,1±6,0%) correspondingly (р=0,2491); fourth pregnancy in 5(19,2±7,7%) and in 4(14,8±6,8%) (р=0,6257). Analysis of ante- and intranatal period in women with multiple and single pregnancies gave evidence that women’s health state and peculiarities of the pregnancy course did not show statistically significant differences (Table 1). The differences were observed during intranatal period course: high rate of surgical delivery and Apgar score less than 6 points during the first minute of life. Apgar score less than 6 points during the fifth minute of life was determined only in 2 newborns (7,6±5,1%) who were born first, and in 2 newborns (7,6±5,1%)who were born second.

Dopplerometric investigation of umbilical bloodstream in infants in bichorionic biamniotic twins during antenatal period has not shown significant differences in the indices except systole/diastole ratio (Table 2).

An increase in median value of systole/diastole ratio of umbilical artery in multiple pregnancy embryos can indicate the advantage of adaptation mechanisms involvement, aimed at an increase in blood flow at systole in umbilical artery to provide blood supply to the fetus.

The results of anthropometric measurement of newborns in observation groups are given in Table 3

At birth more than 10% body mass difference in twins has been observed in 28 out of 52 children (53,8 %), that is discordance occurred in 14 out of 26 (53,8 %) multiple pregnancies with bichorionic biamniotic twins. Median values of gestation age in infants with body mass discordance and without it are given in Figure 1.

Thus, delivery time variability is commonly seen in women with bichorionic biamniotic twins without body mass discordance, difference was not determined by median values of delivery time (37 weeks and 36, 5weeks, р=0,5661).

That is why further analysis of early neonatal course was studied separately in infants who were born first (n=26) and second (n=26) (Table 4), and in discordant pregnancies in a larger infant (n=14) and smaller infant (n=14) (Table 5).

Early neonatal period has not been shown to have differences in first or second infants in bichorionic biamniotic twins, but it has been significantly different from infants in control group: one third of them has been found to have an increase in respiratory distress syndrome cases.

Comparative characteristics of early neonatal course features in body mass discordance more than 10% in multiple bichorionic biamniotic twins have not shown significant differences.

According to V. V. Mit’kov (1996), fetal development discordance can be diagnosed in case of S/D index difference in umbilical arteries more than 0,8 with sensitivity of 64% and specificity of 100% [9]. Our own investigation has allowed us to determine the difference S/D between the fetuses more than 0,8 in 8 out of 26 women (30,7±9,0%) and compare it with the body mass difference at birth. Thus, this difference has been noted in 6 (42,8±13,2%) women, who had children with body mass discordance and in 2 (16,6±10,8%) women whose children have not been found to have a significant body mass difference (р=0,1492) with sensitivity of 42 % (95% DІ 18;70) and specificity of 83% (95% DІ 50;97). Low sensitivity of this test can be explained only by the fact that the study included only the women with bichorionic biamniotic twins, whose fetal development depends on separate own placental complex as distinguished from monochorionic twins, where fetofetal transfusion with “donor-recipient” blood supply disturbance of one fetus is common [2]. This research allowed to compare S/D difference more than 0,8 of umbilical arteries and development discordance of 10%. The authors suggest that the study of fetal umbilical blood flow in discordance of more than 20% or 30% in multiple pregnancie presents many opportunities for further investigation.

We have carried out multiple linear regression, having included anamnesis data for the prognosis of complications development at neonatal period and have not obtained statistical difference which involves further accumulation of data in this direction.

Conclusion:

1. Newborns in multiple pregnancies are more commonly born with the help of Cesarean section and their Apgar score is less than 6 points at the fifth minute of life.

3. Body mass difference in newborn twins of more than 10% can be found in every other multiple pregnancy with bichorionic biamniotic twins.

4. Dopplerography of umbilical blood flow in bichorionic biamniotic tweens fetuses determined an increase in systole-diastole ratio of the umbilical artery.

5. Multiple pregnancy infants regardless of absence or presence of body mass discordance have been noted to have an increase in respiratory distress syndrome frequency during early neonatal period.