Important facts on pregnancy

The National Academy of Sciences recommends a weight gain of 11-16kg (25-35lb) for women of normal weight, 13-18kg (28-40lb) for underweight women, and 7-11kg (15-25lb) for overweight women. The recommended total weight gain for twin pregnancy is 16-20kg (34-45lb).

Energy
Additional energy is necessary to support the metabolic demands of pregnancy and foetal growth. The extra calories needed per day in the first trimester are slight. The energy needs increase to about 300 calories per day for the second and third trimester.

It is difficult to specify the exact energy requirements because these vary with pre-pregnancy weight, amount and composition of weight gain, and stage of pregnancy and activity level. It has been suggested that energy needs be evaluated in terms of individual rate of weight gain.

Low calorie intake can result in the breakdown of stored fat in the mother, leading to the production of ketones in her blood and urine. Ketones production is a sign of starvation of a starvation-like state. Extreme level of ketonemia, may be an indicator of maternal malnutrition, with an increased risk of neonatal death.

Protein
You will need more protein throughout pregnancy, beginning early in gestation, due to the increased need. The exact requirements however vary from woman to woman depending on her prepregnancy nutrition, genetic determinants of fetal size and maternal lifestyle behaviour (King 2000; Kalhan 2000). You will probably have no difficulty eating plenty of it, as protein is the least likely nutrient to be lacking in the diet. Protein is needed for the proper development of the foetus and placenta.

Vitamins
Pregnancy doubles a your need for folic acid. Compromise maternal folate intake is associated with several negative pregnancy outcomes including low birth weight, neural tube defects, pre-term labour and spontaneous miscarriage. Folic acid is important in the development of the neural tube of the fetus. The neural tube closes by 28 days of gestation, before most women realize they are pregnant. Therefore, supplementation with folic acid is highly recommended prior to conception and throughout childbearing years (Honein et al. 2001; Scholl & Johnson 2000; Mahan & Escott-Stump 1996). Moreover, folic acid is more bioavailable than food folate (Bailey 2000).

Pregnant women have an increased need for vitamin B 6. Some scientific evidence suggested that moderate doses may reduce emotional symptoms (depression, irritability, tiredness). This B vitamin has also been administered in managing severe nausea and vomiting of pregnancy (Mahan & Escott-Stump 1996).

A study suggested that vitamin A status be improved during pregnancy and lactation as this will influence the composition of breast milk. However, excessive consumption appears to be teratogenic. Inadequate vitamin A during early pregnancy may account for some paediatric congenital abnormalities. Vitamin A deficiency in infants is strongly associated with depressed immune function and higher morbidity and mortality due to infectious diseases (Zile 2001; Azais-Braesco & Pascal 2000; Ortega et al. 1997; Mahan & Escott-Stump 1996).

The amount of vitamin D required is slightly increased. Vitamin D is needed for its positive effects on calcium balance. Vitamin E requirements are believed to increase somewhat during pregnancy, but deficiency in humans is rare and has not been linked with either damage to offspring or reduced fertility. Usual diets provide adequate amounts of vitamin K (Mahan & Escott-Stump 1996).

Minerals

Approximately 30g of calcium is accumulated during pregnancy, almost all of it in the fetal skeleton (25g). The remainder is stored in the maternal skeleton, presumably in reserve for the calcium demands of lactation (Mahan & Escott-Stump 1996). Several studies revealed a positive association between calcium supplementation and pregnancy-induced hypertension, preeclampsia, maternal health and long-term health benefits for your baby (Prentice 2000; Ritchie & King 2000; Villar& Belizan 2000).

You definitely need extra iron during pregnancy. The increased need is due to the elevated maternal blood supply during pregnancy. Women rarely enter pregnancy with sufficient iron stores to cover all the needs without compromising maternal wellbeing. Maternal anaemia develops in some women who do not use iron supplements. Maternal iron deficiency in pregnancy is associated with preterm delivery and inferior neonatal health (Allen 2000; Mahan & Escott-Stump 1996).

Zinc deficiency might lead to malformation and other poor pregnancy outcomes. Maternal zinc status may also be inversely related to the level of prenatal iron supplementation (Mahan & Escott-Stump 1996). Maternal copper deficiency can lead to various structural and biochemical abnormalities (Keen et al. 1998).

Maternal iodine deficiency has been known to cause cretinism in offspring. Suboptimal iodine nutrition of the mother may also compromise development of her foetus even when cretinism does not occur. Iodine deficiency is now regarded by the WHO as the most preventable cause of brain damage (Hetzel 2000; Mahan & Escott-Stump 1996).

Phosphorus is found in a wide variety of foods and deficiency is rare. The common occurrence of leg cramps at night has been associated to a decline in serum calcium related to a calcium/phosphorus imbalance (Mahan & Escott-Stump 1996).

Pregnancy is a ‘salt-wasting’ condition, where your body can use more salt than usual. The enhanced fluid retention during pregnancy actually increases your body’s demand for sodium. However, moderate intake of salt and other sodium-rich foods is appropriate for everyone (Mahan & Escott-Stump 1996).

References:

Allen, L.H. 2000. Anemia and iron deficiency: effects on pregnancy outcome. Am. J. Clin. Nutr. 71 (5)(suppl): 1280-1284.