Patients with resolution of low-lying placenta and placenta previa remain at increased risk of postpartum hemorrhage.

OBJECTIVE: To determine whether women who experience resolution of low placentation (low-lying placenta or placenta previa) are at increased risk of postpartum hemorrhage compared to those with normal placentation throughout pregnancy. METHODS: This was a retrospective cohort study of women who delivered at Mount Sinai Hospital between 2015 and 2019, and who were diagnosed with low-lying placenta or placenta previa on transvaginal ultrasound at the time of the second-trimester anatomical survey, with resolution of low placentation on subsequent ultrasound examination. Women undergoing second-trimester anatomical survey who had normal placentation on transvaginal ultrasound 3 days before or after the cases were randomly identified for comparison. The primary outcome was the rate of postpartum hemorrhage. Secondary outcomes included the need for a blood transfusion, use of additional uterotonic medication, the need for additional procedures to control bleeding, and maternal admission to the intensive care unit. Outcomes were assessed using a multivariable logistic regression model. RESULTS: A total of 1256 women were identified for analysis, of whom 628 had resolved low placentation and 628 had normal placentation. Women with resolved low placentation, compared to those with normal placentation throughout pregnancy, had significantly higher mean age (33.0 ± 5.4 years vs 31.9 ± 5.5 years; P < 0.01) and lower mean body mass index at delivery (27.9 ± 5.5 kg/m2 vs 30.2 ± 5.7 kg/m2 ; P < 0.01), and were more likely to have undergone in-vitro fertilization, be of non-Hispanic white race, have posterior placental location (all P < 0.01) and have private/commercial health insurance (P = 0.04). Patients with resolved low placentation vs normal placentation had greater odds of postpartum hemorrhage (adjusted odds ratio (aOR), 3.5 (95% CI, 2.0-6.0); P < 0.01), use of additional uterotonic medication (aOR, 2.2 (95% CI, 1.5-3.1); P < 0.01) and increased rates of additional procedures to control bleeding (aOR, 4.0 (95% CI, 1.3-11.9); P = 0.01). CONCLUSION: Despite high rates of resolution of low-lying placenta and placenta previa by term, women with resolved low placentation remain at increased risk of postpartum hemorrhage compared to those with normal placentation throughout pregnancy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Genotypic differences in larval olfactory discrimination in two Drosophila melanogaster strains.

Wild-type (+B) and compound chromosome mutant (bB) Drosophila melanogaster larvae were tested in a U-maze. Fresh Drosophila food or food and larvae were placed in each of the two goals (+B only in goal 1, bB in goal2) and served as stimulus. Separate trials were conducted using +B and bB larvae to test for preference in the maze. Significantly more test larvae went to the arm of the maze containing their own strain as stimulus when (1) both goals contained larvae, (2) one goal contained homogenetic larvae and the other fresh food only, and (3) the goals contained biotic residues of stimulus larvae. The strength of the stimulus necessary to elicit the response differed for the two strains, the +B strain apparently being more sensitive. As the density of the stimulus larvae was increased, the choices of the test larvae became statistically nonsignificant and the number of larvae remaining in the starting arm of the maze increased. The data suggested that the strains of larvae utilized here have the capacity for olfactory discrimination.

Protein synthesis inhibition alters Drosophila mating behavior.

Fruit fly Drosophila pseudoobscura virgin AR females mate preferentially with AR males given a choice between AR and or males. However, AR females which mated with or males when young show a significant change in sexual selection in favor of or over AR males in subsequent simultaneous choice tests. Ingestion of food moistened with 4 ml cycloheximide (400 microng/ml) produces 75% protein synthesis inhibition in the female flies. Females exposed to cycloheximide (CXM) immediately after their initial copulation with or males resemble virgin flies in their choice of mates, and mate preferentially with AR males. Females exposed to CXM before their initial copulatory experience with or males resemble or-experienced but untreated (no CXM) flies in their choice of mates, and mate preferentially with or males. The change in sexual preference shown by females with prior copulatory experience resembles learning in that it is subject to disruption by CXM in ways analogous to those reported in the literature.

Ethological isolation and mating experience in Drosophila paulistorum.

With few exceptions, previously published experiments documenting ethological isolation between Drosophila populations have used young virgin females. We have observed directly females of Drosophila paulistorum semispecies in choice experiments with both homogamic and heterogamic males. Aged females' sexual selection did not differ from that of young females. Previous heterogamic copulatory experience did not change the degree of sexual isolation; however, females with homogamic copulatory experience showed a significantly higher preference for homogamic males.