Placental and fetal Doppler velocimetry in pregnancies complicated by maternal diabetes mellitus.

OBJECTIVE: Our purpose was to investigate placental and fetal circulation in pregnancies complicated by maternal diabetes mellitus and to relate any changes to fetal blood pH, Po2, and hematocrit. STUDY DESIGN: Doppler measurements of both uterine arteries, one umbilical artery, the fetal descending thoracic aorta, and one fetal middle cerebral artery were performed in 65 well-controlled diabetic pregnancies in a cross-sectional study at the Harris Birthright Research Centre for Fetal Medicine, London. In 41 cases cordocentesis was also performed for the measurement of umbilical venous blood pH, Po2, and hematocrit. RESULTS: The mean umbilical venous blood pH was significantly lower and the hematocrit significantly higher than the appropriate normal mean for gestation. However, the Doppler indices of the placental and fetal circulations were essentially normal, except in some of the cases complicated by preeclampsia or intrauterine growth retardation. CONCLUSIONS: Maternal diabetes mellitus is not associated with abnormalities in Doppler indexes of the placental or fetal circulations.

Fetal B lymphocyte subpopulations in normal pregnancies.

In 190 pregnancies undergoing cordocentesis for prenatal diagnosis (n = 174) or elective caesarean section (n = 16), fetal peripheral blood B lymphocyte subpopulations were measured using a fluorescence-activated cell sorter (FACScan). The total number of B lymphocytes and polyreactive CD5+ B cells increased exponentially with gestation from respective means of 0.33 x 10(9)/l and 0.25 x 10(9)/l at 17 weeks to a plateau of 0.66 x 10(9)/l and 0.54 x 10(9) at 36 weeks, remaining at that level thereafter. The number of mature CD10- and active CD23+ B lymphocytes increased linearly from a mean of 0.07 x 10(9)/l and 0.11 x 10(9)/l at 17 weeks to 0.24 x 10(9)/l and 0.37 x 10(9)/l, respectively, at 40 weeks. As expected, all B lymphocytes expressed the HLA-DR antigen from as early as 16 weeks gestation. These alterations in specific B lymphocyte subpopulations reflect the pattern of maturation and development of the fetal humoral immune system.

Fetal T-lymphocyte subpopulations in normal pregnancies.

Peripheral blood T lymphocyte subpopulations were measured, using a fluorescence-activated cell sorter, in fetal blood samples obtained either by cordocentesis (n = 118) or at elective caesarean section (n = 14). Both the numbers and percentages of the total T lymphocytes (CD3+) and T-helper lymphocytes (CD4+) increased exponentially with gestation from respective means of 46% (1.15 x 10(9)/l) and 29% (0.70 x 10(9)/l) at 16 weeks to a plateau of 75% (3.11 x 10(9)/l) and 54% (2.10 x 10(9)/l) at 34 weeks. Similarly, the number of suppressor/cytotoxic T lymphocytes (CD8+) increased linearly with gestation from a mean of 22% (0.55 x 10(9)/l) at 16 weeks to 24% (0.96 x 10(9)/l) at 40 weeks; there were no natural cytotoxic T lymphocytes (CD3+CD56+) in any of the fetal blood samples. The helper-to-suppressor T lymphocyte ratio (CD4/CD8) increased exponentially with gestation from a mean of 1.22 at 16 weeks to 2.57 at 28 weeks. The alterations in T lymphocyte subpopulations were accompanied by changes in the expression of CD45RA, L-selectin, CD25 and HLA-DR. These alterations in T lymphocyte subpopulations with gestation reflect the pattern of maturation and development of the fetal cell-mediated immune system.