Causes

Recognizing that low birthweight may be due to either IUGR or preterm delivery, and, in some cases, a combination of the two, the scientific community has progressively started to consider that IUGR and preterm delivery are two conditions likely caused by various and possibly independent etio-pathological factors.

Several complications of pregnancy, such as pre-eclampsia, fetal distress, fetal growth restriction, abruptio placenta, fetal death, placenta previa, and multiple gestations, are associated with preterm delivery, either spontaneous or induced. Importantly, developments in obstetric and neonatal care, and the consequent increase in obstetric interventions, are likely to be associated with the increase in rates of preterm delivery observed in recent years. Although several lifestyle factors and conditions have been implicated as possible causes, a definitive etiology has not been determined, making it difficult to identify women at risk and to implement preventive strategies. Poor nutrition, cigarette smoking, and alcohol and drug abuse have been indicated as possible risk factors, as well as young maternal age, poverty, short stature, occupational factors, and psychological stress. In addition, genetic factors are likely to be involved in the etiopathogenesis of pre-term delivery, as suggested by the fact that the condition tends to recur in families and that prevalence varies across races. The possible role of infection in triggering preterm delivery has been suggested by several studies that have shown associations between delivery before term and amniotic fluid and chorioamniotic infection, bacterial vaginosis, genitourinary clamydial infection, and periodontal disease. Despite the biological plausibility of these associations, their causal relationship has not been definitely proved by unequivocal scientific and epi-demiological evidence.

Several conditions have been associated with intrauterine growth restriction. However, present knowledge of the process of fetal growth is limited by the difficulty of differentiating between constitutional and environmental determinants of fetal growth. This limitation complicates the investigation of an important determinant of fetal growth such as maternal size. Small women tend to have smaller babies. There is evidence that intergenerational effects on birth weight are transmitted through the maternal line, thus suggesting a genetic effect. However, poor maternal nutrition and social deprivation have been related to impaired fetal growth and may also be related to small maternal size. Similarly, the relationship between fetal size and race may be mediated by genetic and environmental factors. Specifically designed studies are necessary to determine the contribution of genetic and environmental determinants to the process of fetal growth.

Other factors that have been associated with fetal growth restriction are fetal infections, congenital malformations, chromosomal abnormalities, chemical teratogens, vascular disease such as preeclampsia, chronic renal disease, chronic hypoxia, placental and cord abnormalities, and multiple fetuses.

Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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