X-rays are known to have possible adverse effects on the development of the fetus, and the risks need to be weighed against the benefits.Congenital disorders are acquired before birth. Infants with certain congenital heart defects can survive only as long as the ductus remains open: in such cases the closure of the ductus can be delayed by the administration of prostaglandins to permit sufficient time for the surgical correction of the anomalies. Conversely, in cases of patent ductus arteriosus, where the ductus does not properly close, drugs that inhibit prostaglandin synthesis can be used to encourage its closure, so that surgery can be avoided. Other heart birth defects include ventricular septal defect,  pulmonary atresia, and tetralogy of Fallot. An abdominal pregnancy can result in the death of the fetus and where this is rarely not resolved it can lead to its formation into a lithopedion. Fetal pain
Fetal pain, its existence and its implications are debated politically and academically. According to the conclusions of a review published in 2005, "Evidence regarding the capacity for fetal pain is limited but indicates that fetal perception of pain is unlikely before the third trimester." However, developmental neurobiologists argue that the establishment of thalamocortical connections (at about 6+1⁄2 months) is an essential event with regard to fetal perception of pain. Nevertheless, the perception of pain involves sensory, emotional and cognitive factors and it is "impossible to know" when pain is experienced, even if it is known when thalamocortical connections are established.
Low birth weight increases risk for perinatal mortality (death shortly after birth), asphyxia, hypothermia, polycythemia, hypocalcemia, immune dysfunction, neurologic abnormalities, and other long-term health problems. SGA may be associated with growth delay, or it may instead be associated with absolute stunting of growth. Viability
Fetal viability refers to a point in fetal development at which the fetus may survive outside the womb. The lower limit of viability is approximately 5+3⁄4 months gestational age and is usually later.There is no sharp limit of development, age, or weight at which a fetus automatically becomes viable. According to data from 2003 to 2005, survival rates are 20–35% for babies born at 23 weeks of gestation (5+3⁄4 months); 50–70% at 24–25 weeks (6 – 6+1⁄4 months); and >90% at 26–27 weeks (6+1⁄2 – 6+3⁄4 months) and over. It is rare for a baby weighing less than 500 g (1 lb 2 oz) to survive.When such premature babies are born, the main causes of mortality are that the respiratory system and the central nervous system are not completely differentiated. If given expert postnatal care, some preterm babies weighing less than 500 g (1 lb 2 oz) may survive, and are referred to as extremely low birth weight or immature infants.Preterm birth is the most common cause of infant mortality, causing almost 30 percent of neonatal deaths. At an occurrence rate of 5% to 18% of all deliveries, it is also more common than postmature birth, which occurs in 3% to 12% of pregnancies.