These protocols have lower sensitivities (60%) and higher specificities (99%), but similar positive predictive values or rates of false positives, compared with protocols for trisomy 21 screening, because these conditions are much more rare.29A new technology, noninvasive prenatal diagnosis, offers the possibility of screening for aneuploidies and other conditions by identifying fragments of fetal DNA in maternal circulation.
Women at risk of preeclampsia should be offered low-dose aspirin prophylaxis, as well as calcium supplementation if dietary calcium intake is low. women receiving prenatal care has steadily increased.1 Family physicians provide integrated prenatal care, including evidence-based screening, counseling, medical care, and psychosocial support.
Induction of labor may be considered between 41 and 42 weeks' gestation. There is uncertainty about the critical elements of prenatal care and education, but inadequate care is associated with increased complications.24Although women in developed countries often have seven to 12 prenatal visits, a multinational trial showed that decreasing the visits to a minimum of four did not increase adverse outcomes, although it slightly decreased patient satisfaction with care.5 Prenatal care that is provided by a small team; is coordinated; and follows an evidence-based, informed process results in fewer prenatal admissions, improved prenatal education, and greater satisfaction with care.6A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series.
Many elements of routine prenatal care are based on tradition and lack a firm evidence base; however, some elements are supported by more rigorous studies.
Correct dating of the pregnancy is critical to prevent unnecessary inductions and to allow for accurate treatment of preterm labor.
Intramuscular or vaginal progesterone should be considered in women with a history of spontaneous preterm labor, preterm premature rupture of membranes, or shortened cervical length (less than 2.5 cm).
Screening for diabetes should be offered to all pregnant women between 24 and 28 weeks' gestation.
Prenatal screening for fetal aneuploidy in singleton pregnancies If a screening test is positive for Down syndrome, the woman should be offered amniocentesis (15 weeks' gestation or later) or chorionic villous sampling (11 to 13 weeks).
The rates of excess fetal loss with these two procedures are similar.29 In centers where both procedures are available, women can consider earlier genetic testing options.611A combination of serum and nuchal translucency testing can also screen for other trisomy syndromes, such as 13 and 18.
Most laboratories can report the risk of trisomy 18 syndrome using serum testing.
Protocols for the detection of other trisomies can detect a large portion of these anomalies.
Screening and treatment for iron deficiency anemia can reduce the risks of preterm labor, intrauterine growth retardation, and perinatal depression.