Placenta previa is not an independent risk factor for a small for gestational age infant

Article Abstract:

The terms intrauterine growth retardation (IUGR) and small for gestational age (SGA) refer to conditions of delayed growth and development of the fetus during pregnancy. These conditions occur in 16 to 19 percent of pregnancies complicated by placenta previa, in which the placenta, the tissue from which the fetus derives nutrition, is abnormally implanted in the lower portion of the uterus. Placenta previa ia associated with bleeding and an increased risk of infection. Impairment of the placenta may contribute to the development of IUGR in placenta previa. Because the placenta may be implanted at a site with a poor blood supply, the transport of nutrients to the fetus may be adversely affected. However, previous studies demonstrating a relation between placenta previa and IUGR were generally poorly designed and did not account for other factors that might contribute to the development of IUGR. These studies were unable to show an association between placenta previa and an increased incidence of SGA infants. The placenta has a reserve, or surplus of nutritional stores, that may be used under conditions of nutritional shortage. In addition, methods of managing placenta previa have improved. The relation between placenta previa and the risk of birth of an SGA infant was assessed for 54,969 births at three hospitals between 1980 and 1990. Placenta previa was diagnosed in 179 single-fetus pregnancies. The study also included 171 women without placenta previa, who were similar in race, gestational age, number of viable pregnancies, and fetal sex to women with placenta previa. SGA fetuses were identified in 7 of 171 pregnancies complicated by placenta previa and 10 of 171 normal pregnancies. The average birth weights were similar for both groups. These findings suggest that placenta previa is not associated with an increased risk of birth of SGA infants. Hence, pregnancies complicated by placenta previa do not require routine monitoring of fetal growth by ultrasound. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Fetus, Fetal growth retardation, Placenta, Placenta praevia, Placenta previa

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Calculated risk of chromosomal abnormalities in twin gestations

Article Abstract:

Pregnancy with twins presents a special problem in genetic counseling. For dizygotic twins (fetuses from two eggs - the most common case), the risk of chromosomal defects is twice that of a single pregnancy. To provide information relevant to this issue, tables are presented that list the risks of chromosomal abnormalities in twin pregnancies (dizygotic or monozygotic) in mothers of different maternal ages. In constructing such tables, the rate of dizygosity in the population under study must be considered; in this case, the rate was approximately 80 percent. At any age, the risk for an abnormality in one or both fetuses equals the sum of three possibilities: the probability that one is affected (dizygotic), the probability that both are affected (dizygotic); and the probability that both are affected (monozygotic). The formulas used to calculate the probability of a chromosomal defect are presented. Results show that, while the risk of having one twin affected by Down syndrome is always greater than for a singleton pregnancy, the chance that both twins are affected is small. A patient aged 33 who is pregnant with twins has a risk equivalent to that of a 35-year-old woman with a singleton pregnancy (1/347 and 1/385). However, the 33-year-old's risk of having both twins affected is 1/3,105. Rates for chromosomal aberrations other than Down syndrome are included. Recent medical developments have made it possible to terminate only one member of a pair of twins, in contrast to earlier times when chromosomal abnormality meant termination of the pregnancy (if the woman so desired). Selective termination, however, presents important ethical, moral, and emotional problems. Before a prenatal diagnostic procedure is undertaken, the procedure-related fetal loss rate must be weighed against the likelihood that the fetuses have a significant chromosomal defect. Larger studies are needed to confirm the age-related rates presented here. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Statistics, Demographic aspects, Genetic aspects, Ethical aspects, Pregnancy, Chromosome abnormalities, Genetic counseling, Pregnancy, Multiple, Multiple pregnancy, Middle aged women, Pregnancy in middle age

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Management of parvovirus infection in pregnancy and outcomes of hydrops: a survey of members of the Society of Perinatal Obstetricians

Article Abstract:

Infection with parvovirus during pregnancy can contribute to hydrops in the fetus, a potentially fatal massive accumulation of fluid. In a survey of members of the Society of Perinatal obstetricians, 541 respondents confirmed parvovirus-induced hydrops. In 34% of the cases, there was spontaneous resolution; in 30% of the cases there was death without uterine tranfusion. After uterine transfusion, 29% cases resolved, while 6% died. Almost all of the cases appeared between 16 and 32 weeks.

Care and treatment, Patient outcomes, Mortality, Pregnancy, Complications of, Pregnancy complications, Hydrops fetalis, Parvovirus infections

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