Medical care and pregnancy: common preconception and antepartum issues

Introduction A general approach to women of reproductive age should include consideration of the possibility of pregnancy. The preconception approach to medical care includes optimization of chronic health problems and risks that may impact negatively on pregnancy. Medical care of women in pregnancy requires understanding of changes in maternal physiology and special risks to the fetus or mother. The preconception approach to medical care Preconception counseling Most women do not need special diagnostic testing or therapeutic interventions before the initiation of pregnancy. In general, women without chronic illness may undertake pregnancy with general preventive counseling for a healthy diet, avoidance of substance abuse, regular exercise, and common occupational precautions. This should be a part of preventive care in all young women. Most women without chronic disease should be able to undertake pregnancy healthily with advice about a healthy diet, avoiding abuse of substances, taking regular exercise, and common occupational precautions. Dietary precautions Low levels of serum and red blood cell folic acid have been demonstrated to increase the risk of neural tube defects. In randomized clinical trials, 0.8 mg of folic acid per day decreased the occurrence of neural tube defects and 4 mg of folic acid per day decreased the recurrence of neural tube defects.1 Lower effective doses were found in non-randomized trials; current recommendations from the Institute of Medicine and the US Public Health Service recommend 0.4 mg/day in women of childbearing potential.2 A populationbased study of birth registries in Europe, NorthAmerica, and Australia demonstrated significant reduction of neural tube defects occurring with fortification of food products but not with recommendation of supplementation alone.3 Fortification of flour is mandatory in Canada, the USA, and Chile, but not in most European countries. A study of low-income women found that significant numbers of women still had diets deficient in folic acid, and most had no knowledge of the foods that they should be eating to achieve a healthy level in their diet.4 At the same time, women with higher educational levels may be taking supplementation that is not recommended or needed, such as vitamin A, but still have diets deficient in folic acid.5 Thus supplementation with a multivitamin or folic acid seems warranted at this time in all women of childbearing potential, and higher levels of supplementation (4 mg/day) in high risk women.6 These include women with a history of a previous delivery of a child with a neural tube defect, women with a strong family history of neural tube defects, and women on antiepileptic drugs (AEDs). Fortification of grain products is ideal to achieve the greatest certainty of attaining optimal serum folate levels and prevention of neural tube defects. In countries that do not use fortification, all women of childbearing potential should be supplemented with folic acid 0.4 mg daily and 4–5 mg/day in high risk women. Strength of recommendation A. Occupational concerns Women with occupational exposures often seek specific information regarding the safety of pregnancy. This complex issue may be viewed from a number of perspectives, including the very personal concerns of the patient for her baby’s well-being and her family’s economic viability. Although much attention has been focused on maternal occupational exposures, a number of substances appear to cause subfecundity (reduced fertility) or other adverse pregnancy outcomes as a result of paternal exposures. Policies in US industries that exclude women from certain types of job may, therefore, be viewed as discriminatory. From a more general perspective, these exclusionary practices may be shortsighted if they preclude a goal of occupational safety for all workers. Legislative issues have been approached differently in a number of European countries compared with the USA, with special maternity leave status granted to 1% and 0.1% of women in Denmark and Finland respectively, whose occupation is judged to be sufficiently hazardous to exclude participation during pregnancy.7 Table 9.1 provides a brief overview of occupational exposures that are known to be associated with adverse pregnancy outcome. A number of possible exposures have been studied in pregnancy in an effort to decrease associated risk by protective practices. In health care positions, measurements of radiation with exposure to nuclear medicine patients receiving technetium-99m or iodine-131 have led to recommendations on limits for technologists and nursing staff.8 Changes in the practice of an occupation may affect risk. A study of hairdressers examined the high rate of adverse pregnancy outcomes in two time periods, 1986–88 and 1991–93 in hairdressers as compared to sales clerks. However, this study also demonstrated a decline in the higher incidence of spontaneous abortions and low birth weight infants in hairdressers between the two periods.9 This may be the result of changes in products used by the hairdressers. Exposure to anesthetic gases appears to have diminished among operating room personnel, but exposures may still remain at an unacceptable level for recovery room and surgical intensive care unit personnel caring for recovering post-anesthetic patients unless scavenging devices are in operation in these work zones.10 Radiation
The issue of occupational exposure to radiation includes workers from several industries.
Lower limits of exposure apply to pregnant women working in fluoroscopy suites than to non-pregnant individuals.
In the USA, these limits apply with voluntary declaration of pregnancy. Appropriate use of protective clothing can limit radiation exposure to recommended levels.11
The theoretical risk of cosmic radiation at high altitudes has been included in considering risks encountered by pregnant flight attendants and frequent business travelers. However, actual measurements of airline crews have failed to demonstrate doses of radiation exceeding the recommended limits to exposure.12 Adverse pregnancy outcomes and childhood malignancy have been studied in workers at nuclear plants with adverse pregnancy outcomes (stillbirth) noted in paternal exposures to external ionizing radiation,13 and possible increase in childhood cancers seen in children whose mothers experienced radiation work exposures.14 Stress
Occupational stress, especially physical stress, has been widely suspected by physicians and patients of causing adverse pregnancy outcomes, but most women are able to work safely throughout their pregnancies without difficulties. Physical stresses that have been associated with increased rates of prematurity and low birth weight include prolonged standing, long hours, protracted ambulation, and heavy lifting.15
Studies that examine these issues vary considerably in design and may include confounding factors, thus creating methodological concerns.
One study found greater risk of preterm birth, low birth weight, and small-for-gestational age birth in textile workers, food service workers, electrical equipment operators, and janitors when compared with women employed as clerks, teachers, and librarians.16 Another study found higher rates of preterm deliveries and low birth weight in nurses than in bank workers.17,18 A self-report survey of female physicians found higher rates of stillbirth and premature delivery than in the general population.18 However, a large cohort study of more than 7000 women found only a modest increase in risk of preterm delivery (OR ¼ 1.31) for women whose occupation entailed more than eight hours standing per day. In addition, this study found no increase in low birth weight or preterm delivery with heavy work or exercise after controlling for confounding variables, suggesting that other socioeconomic factors might account for differences in pregnancy outcome.19

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