SummaryPerinatal morbidity and mortality rates for vasa previa are high when it is not diagnosed antenatally. In this report, a case of vasa previa in a twin pregnancy was diagnosed postnatally, which leads to complications with the first twin. Serial ultrasound during pregnancy did not diagnose a bilobed placenta, a velamentous insertion of the umbilical cord or vasa previa. At 37 weeks, vaginal bleeding was detected in the expulsive stage and vaginal-assisted delivery of both fetuses was undertaken. The first fetus was born pale and anaemic, and required a blood transfusion and therapeutic hypothermia. A high risk of vasa previa is associated with placentas with low-lying insertion, bilobed placentas, velamentous insertions of the umbilical cord, multiple pregnancy and pregnancies conceived after the use of assisted reproductive technologies. Transvaginal ultrasound screening with colour flow Doppler can allow antenatal diagnoses of vasa previa and an improved outcome. BACKGROUND

This study aimed to evaluate the influence of initial weight, initial age, average daily gain in initial weight, average daily gain in total weight and genetic group on the probability of pregnancy in primiparous females of the Nellore, ½ Simmental + ½ Nellore, and ¾ Nellore + ¼ Simmental genetic groups. Data were collected from the livestock file of the Farpal Farm, located in the municipality of Jaíba, Minas Gerais State, Brazil. The pregnancy diagnosis results (success = 1 and failure = 0) were used to determine the probability of pregnancy that was modeled using logistic regression by the Proc Logistic procedure available on SAS (Statistical…, 2004) software, from the regressor variables initial weight, average daily gain in initial weight, average daily gain in total weight, and genetic group. Initial weight (IW) was the most important variable in the probability of pregnancy in heifers, and 1-kg increments in IW allowed for increases of 5.8, 9.8 and 3.4% in the probability of pregnancy in Nellore, ½ Simmental + ½ Nellore and, ¾ Nellore + ¼ Simmental heifers, respectively. The initial age influenced the probability of pregnancy in Nellore heifers. From the estimates of the effects of each variable it was possible to determine the minimum initial weights for each genetic group. This information can be used to monitor the development of heifers until the breeding season and increase the pregnancy rate.