[Intrauterine growth characteristics of twins and those twins discordant birthweight].

OBJECTIVE: To investigate the intrauterine growth characteristics of twins and birthweight discordant twins (discordant twins). METHODS: Total of 1010 twin pregnancies (2020 fetuses) with complete delivery records from the Department of Obstetrics and Gynecology, the First and Third Affiliated Hospital of SUN Yat-sen University between January 1, 2000 and July 31, 2010 were studied retrospectively. One handred and ninteen cases (238 fetuses) with intrapair birthweight difference ≥ 25% were determined as the discordant twins group, and the other 891 cases (1782 fetuses) with intrapair birthweight difference < 25% were identified as the concordant twins group. The singleton control group included 4042 singleton pregnancies in the same period. RESULTS: (1) Comparison of clinical data between the twins groups: the birthweight of larger-twin, smaller-twin and intrapair birthweight difference in the discordant twins group and the concordant twins group were (2090 ± 827) g, (1392 ± 592) g, (33.9 ± 9.3)%, and (2408 ± 543) g, (2191 ± 505) g, (8.9 ± 6.5)%, respectively, with significant differences (P < 0.01). The incidence of discordant twins was 11.78% (119/1010). Compared with the concordant twins group, the discordant twins group had higher proportion of monochorionic twins, and higher prevalence of pregnancy complications such as late miscarriage, abnormal umbilical insertion, twin-twin transfusion syndrome and hypertensive disorders in pregnancy (P < 0.05). (2) The characteristics of twin birthweight distribution: 1) In all the 2020 twins, 80.05% (1617/2020) fetuses had birthweight below the 50(th) percentile of the singleton control group, while 23.71% (479/2020) feeuses got birthweight below the 10(th) percentile of the singleton control group. 2) After 19(th) gestational week, the 50(th) and 90(th) percentile of all twins' birthweight were lower than those of singletons. After 38(th) gestational week, the birthweight of singletons kept increasing and reached its peak at 41(th) week, while the birthweight of twins reached its peak at 38(th) week, followed by a decline at 39 weeks, which was even lower than the 10(th) percentile of the singleton control group. 3) The distribution of birthweight of larger- and smaller-twin in the discordant twins group: 65 (54.6%, 65/119) larger-twins and one (0.8%, 1/119) smaller-twin had birthweight above the 50(th) percentile of all twins, while 5 (4.2%, 5/119) larger-twins and 97 (81.5%, 97/119) smaller-twins got birthweight below the 10(th) percentile of all twins. CONCLUSIONS: (1) The patterns of birthweight curves for each gestational week are different between twins and singletons. In order to evaluate the growth of twins, birthweight reference for twins should be employed. (2) According to the reference of twins birthweight, the most discordant twins are complicated with fetal growth restriction at least in one twin.

[Spectral karyotyping of seven prenatally detected marker chromosomes and complex chromosome aberrations].

OBJECTIVE: To perform spectral karyotyping (SKY), fluorescence in situ hybridization (FISH) and conventional karyotyping on prenatally detected marker chromosomes and complex chromosomal aberrations. METHODS: Five marker chromosomes and 2 complex chromosome aberrations diagnosed by G banding were collected. SKY was performed to verify the composition of marker chromosomes. FISH was used to confirm the diagnosis when necessary. In certain cases, C or N banding technique was employed to verify the composition of chromosomes. Results of ultrasonography and pregnancy outcome were reviewed. RESULTS: Among the 5 marker chromosomes, 2 were large and 3 were medium in size, 4 were de novo and one was inherited from the father. By SKY analysis, 2 marker chromosomes have originated from non-acrocentric chromosomes (4 and 9), whilst the other two have originated from acrocentric chromosomes (21 and 22). The remainder was derived from X chromosome. The SKY results were confirmed by FISH in 3 cases. Four cases have chosen to terminate the pregnancy after genetic counseling. A fetus with inherited paternal marker chromosome was delivered at term, and showed normal development during the first year of life. As for the other 2 cases with complex chromosome aberrations, by SKY examination, one had duplication in chromosome 8 and the other had chromosome rearrangements derived from translocation between chromosomes 2 and 6. In the latter case the fetus was delivered at term but showed developmental retardation at 6 months. CONCLUSION: SKY in combination with FISH can facilitate identification of the origins of marker chromosomes as well as complex chromosomal aberrations. With combined information from ultrasonography, SKY and FISH, effective counseling may be offered to the patients.