PREGNANCY, EFINITIONS AND BACKGROUND
Women who are interested in becoming pregnant need a “preconception risk assessment” (March of Dimes, 2009).
They should be aware of their personal genetic biomarkers that could cause problems with infertility, pregnancy, childbirth, or chronic diseases.
Pregnancy is an anabolic state that affects maternal tissues using hormones synthesized to support successful pregnancy. Progesterone induces fat deposition to insulate the baby, supports energy reserves, and relaxes smooth muscle, which will cause a decrease in intestinal motility for greater nutrient absorption.
Estrogen increases tremendously during pregnancy for growth promotion, uterine function, and water retention. Progesterone and estrogen secreted during pregnancy in combination also help prepare for successful lactation.
Adequate weight gain is needed to ensure optimal fetal outcome. Underweight is associated with small for gestational age (SGA) or preterm deliveries. Energy costs of pregnancy vary by the BMI of the mother (Butte et al, 2004).
Tissue growth in pregnancy is approximately: breast, 0.5 kg; placenta, 0.6 kg; fetus, 3–3.5 kg; amniotic fluid, 1 kg; uterus, 1 kg; increase in blood volume, 1.5 kg; and extracellular fluid, 1.5 kg. Rapid weight losses or gains are not desirable during pregnancy.
Higher maternal weight before pregnancy increases the risk of late fetal death, although it protects against the delivery of an SGA infant. Obesity increases risk of first trimester.
or recurrent miscarriages and the need for caesarean delivery; obesity should be corrected before pregnancy whenever possible (Rasmussen and Yaktine, 2009).
Some obese women will seek bariatric surgery to enhance fertility. Women who have had bariatric surgery usually have a positive outcome (Maggard et al, 2008).
A short span between pregnancies or an early pregnancy within 2 years of menarche increases the risk for preterm or growth-retarded infants. Maternal nutrient depletion of energy and protein leads to poor nutritional status at conception and may alter pregnancy outcomes.
Poor maternal iron and folate intakes have been associated with preterm births and intrauterine growth retardation, two outcomes for which women with early or closely spaced pregnancies are at high risk.
Brain development starts during pregnancy and continues into adulthood. Deficiency of various micronutrients has long-term implication for cognitive development . Major diseases including heart disease, hypertension, and type 2 diabetes may originate from impaired intrauterine growth and development as consequences of an insult at a critical, sensitive time. People who are small or disproportionate (thin or short) at birth may later have CHD, high BP, high cholesterol concentrations, and abnormal glucose–insulin metabolism, independent of length of gestation .
Nutritional deficits are serious during pregnancy. Living with marginal food security has been found to correlate
with greater weight gain, more complications, and gestational diabetes . Planned pregnancies usually have the most favorable outcomes. Continuous dietary monitoring of pregnant women and pregnant
teens is essential, especially for calcium, iron, folate, vitamins A, C, B6, and B12 .
Other nutrients of importance include magnesium, fiber, zinc, vitamin D, and biotin. Many cardiac defects may be prevented by maternal use of multivitamins during the periconceptual period.
To prevent SGA births, a mother is encouraged not to smoke, to manage any cardiac disease or conditions such as elevated blood pressure (BP), and to gain sufficient weight. Women who are HIV positive may experience undesirable weight loss.
Bulimia nervosa during pregnancy can lead to miscarriage, inappropriate weight gain (excessive or inadequate), complicated delivery, low birth weight (LBW), prematurity, infant malformation, low Apgar scores, and other problems.
Women with unmanaged PKU may also have poor reproductive outcomes. Prevention requires initiation of the low Phe diet before conception or early in pregnancy, with metabolic control and sufficient intake of energy and proteins.
For twin and multiple pregnancies, twice-monthly visits, sufficient energy intake, multimineral supplementation, and patient education may reduce complications such as LBW and neonatal morbidity.
The American Dietetic Association suggests at least three visits for medical nutrition therapy in high-risk pregnancies. The individual may require more visits if there are complex or multiple risk factors, such as diabetes and celiac disease.
Prenatal Risk Assessments and Indicators of Potentially Poor Outcomes
Prepregnancy
• Adolescence (poor eating habits, greater needs for growth of teen and fetus).
• History of three or more pregnancies in past 2 years, especially miscarriages.
• History of poor obstetrical/fetal performance.
• Overweight and obesity, which can cause a higher risk for gestational diabetes, preeclampsia, eclampsia,
C-section, and/or delivery of infant with macrosomia.
Prepregnancy or During Pregnancy
• Economic deprivation.
• Food faddist; smoker; user of drugs/alcohol; practice of pica with related iron or zinc deficiencies; anorexia
nervosa or bulimia.
• Modified diet for chronic systemic diseases, such as diabetes, celiac disease, PKU.
• Prepartum weight of less than 85% or more than 120% of desirable BMI for height and age; these may
reflect inability to attain proper weight or poor dietary habits.
• Deficient Hgb (11 g) or hematocrit (Hct) (33%) with medical diagnosis of anemia. • Weight loss during PG or gain 2 lb/month in the last two trimesters; dehydration; hyperemesis.
• Risk of toxemia (2-lb weight gain per week or more).
• Poorly managed vegetarian diet, especially vegan diet without supplementation.
• Poor nutrient or energy intakes over the duration of the pregnancy.
• Poor intake of magnesium, zinc, calcium, iron, folate, vitamins A and C, and other key nutrients.