Incidence of spontaneous abortion among normal women and insulin-dependent diabetic women whose pregnancies were identified within 21 days of conception

Experimental diabetes impairs rat embryo development during the preimplantation period

Congenital malformations and early fetal losses are still the main complications of diabetic pregnancy. Whether the diabetic state affects the early embryo development during the preimplantation period is not known. To understand better the early steps of embryo growth, we collected the embryonic structures from the uterine horns of pregnant diabetic rats on day 5 of pregnancy. Diabetes was induced by streptozotocin (50 mg/kg) injection, 7, 14 or 21 days before mating. The morphological analysis revealed a lower rate of blastocysts (72% of all structures) and an increased rate of morulae (19.5%) in diabetic rats, compared to control animals (86.7 and 7.9% respectively). Hence, diabetic rats had fewer blastocysts (5.5 +/- 2.9 per rat) and more morulae (1.5 +/- 1.7) than control animals (7.2 +/- 2.7 and 0.66 +/- 1.2 respectively). Moreover, blastocysts from diabetic rats had fewer nuclei (26.9 +/- 7.3 per blastocyst) than blastocysts from control animals (31 +/- 6.1). In another set of experiments, subdiabetogenic doses of streptozotocin were administered. In rats injected with 25 mg/kg, neither the glycaemia, nor the morphological aspects of the embryos, nor the number of blastocyst nuclei differed from the control animals. In the animals receiving 35 mg/kg, the glycaemia was increased to approximately twice the control group value. However, the embryonic morphology and the nuclei counting of the blastocysts were similar to those of the fully diabetic group injected with 50 mg of streptozotocin. These results show that experimentally induced diabetes, even of a rather mild degree, affects the embryo development during the preimplantation period. The recovered embryos appear less mature and less developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Oestrogen receptor B-region polymorphism and spontaneous abortion in women with breast cancer

To examine whether a variant human oestrogen receptor gene, which differs from the wild-type gene in the B region, was associated with spontaneous abortion, obstetric histories of breast cancer patients with this variant were compared with those of breast cancer patients with the wild-type gene. In women with the B-variant, 50% of pregnancies ended in spontaneous abortion, compared with 10% for women homozygous for the wild-type gene. B-variant women also had a higher proportion of spontaneous abortions and a higher number of spontaneous abortions per woman than did those with the wild-type gene.

Relationship between haemoglobin A1C in early type 1 (insulin-dependent) diabetic pregnancy and the occurrence of spontaneous abortion and fetal malformation in Sweden

This prospective nationwide study examined the relationship between diabetic control in early pregnancy as assessed by HbA1C and the incidence of spontaneous abortion and fetal malformation. HbA1C and plasma C-peptide were determined in 532 women with Type 1 (insulin-dependent) diabetes mellitus, corresponding to approximately 80% of all the diabetic pregnancies in the country during the study period 1982-1985, and 222 non-diabetic control women. Median gestational week for sampling was 9.0 in the Type 1 diabetic and 10.0 in the control group. The median value of HbA1C was 7.7% in the diabetic and 5.3% in the control group (p less than 0.001). The rates of spontaneous abortion, 7.7% vs 7.2%, and malformation, 4.3% (major 2.0%) and 2.4% (major 1.0%), were not significantly different between the diabetic and control group, respectively. These rates of malformation were not significantly different from the national figures of 4.55% (major 1.75%). Much elevated HbA1C, i.e., greater than 10.1% equal to 8 SD above the normal mean control value, was significantly associated with the occurrence of spontaneous abortion (p less than 0.001) and malformation (p less than 0.01). Discriminant analysis revealed that after correction had been made for the significant value of HbA1C to predict the occurrence of spontaneous abortion and malformation, no further predictive power was displayed by measurable plasma C-peptide, maternal age or duration of diabetes or presence of diabetic microangiopathy. We conclude that poor metabolic control in early pregnancy contributes to an increased risk of both spontaneous abortion and fetal malformation.

Incidence and timing of pregnancy losses: relevance to evaluating safety of early prenatal diagnosis

Knowing the frequency and timing of pregnancy loss during normal gestation is integral to evaluating the safety of prenatal diagnostic techniques. That preclinical loss rates are high in humans has long been suspected, but in the past decade new data concerning these losses have become available. Cohort studies indicate that many women who show positive beta-HCG assays never show clinical evidence of pregnancy. Cytogenetic abnormalities have also recently been documented in 20% of ostensibly normal in vitro fertilization embryos. All the above are consistent with the sentinel studies of Hertig and Rock, who showed high frequencies of morphological abnormalities in preimplantation embryos. The frequency of fetal losses after clinical recognition of pregnancy is 12-15%; however, more sensitive (ultrasonographic) methods of detecting fetal demise now indicate that most clinically recognized pregnancies occur prior to 8-9 weeks, being retained in utero 2-3 weeks prior to expulsion. Loss rates are influenced by maternal age, smoking, alcohol, and other confounding variables that if not taken into account could yield spurious results concerning safety of prenatal diagnostic techniques. After 8 weeks gestation the likelihood of losing a viable pregnancy is only 3% and after 16 weeks only 1%.

High glucose levels decrease proliferation of cultured human fetal cells from placenta

We used the placenta as a source of undifferentiated cells to study the effect high glucose levels can have on human fetal cell proliferation in vitro. Cells were subcultured in a modified minimum essential medium with 10% fetal bovine serum containing either 5.5 mmol/L (100 mg/dl) D-glucose (control), 11 mmol/L (200 mg/dl) D-glucose, or 22 mmol/L (400 mg/dl) D-glucose. Cells grown in mannitol-containing media were used as controls for osmolality. After 3 and 7 days' growth in different media, the labeling index was determined by autoradiographic analysis, and cell numbers were determined with a Coulter counter. The labeling indices for cells grown 3 days in 11 or 22 mmol/L D-glucose were 89% (p less than 0.002) and 84% (p less than 0.001), respectively, of control cells grown in 5.5 mmol/L D-glucose. After 7 days' growth, the labeling indices of cells grown in 11 or 22 mmol/L D-glucose were 84% (p less than 0.002) and 70% (p less than 0.001), respectively, of cells grown in 5.5 mmol/L D-glucose media. There was a significant decrease in the number of cells present at both 3 and 7 days in cultures grown in 22 mmol/L D-glucose compared with control. We conclude that a few day's exposure to high glucose levels can have an effect on proliferation of human placental cells in vitro. We suggest that a glucose effect on proliferation of other cells derived from the products of conception might be one mechanism contributing to abnormal development in some pregnancies of diabetic women.