Nutrition in pregnancy

Nutrition and Pregnancy

The significant physiological changes that occur to pregnant women, as well as the extensive period of fetal growth, both require adequate nutrition during the important period of 40 weeks of gestation. Both the maternal under-nutrition with resultant risk to the fetus of growth restriction and prematurity and maternal over-nutrition with the risks of maternal gestational diabetes and the resultant risk of development of obesity in the off-spring, all make dietary considerations in pregnancy very important for the long-term future of the child.

Therefore at your first antenatal visit your obstetrician or health care provider will try and get some sort of understanding of what your diet is like including what it is like during the first trimester of pregnancy. It is always best to be proactive and if you have a problem with under-nutrition, maternal obesity, diabetes, food allergies, other medical conditions which interfere with nutrition then you really should see a qualified dietician who has a good understanding of pregnancy during this first trimester.

Common sense is crucial with respect to diet and having mainly an unprocessed, healthy diet with the appropriate use of vitamins and minerals and appropriate weight gain are all important parts of a normal pregnancy. If you have an average body weight with a BMI of 18 – 25 then an average weight gain in pregnancy will be somewhere between 12kg and 15kg.  If you are mildly obese with a BMI between 25 and 30 aim for a weight gain in pregnancy of somewhere between 7kg and 12kg.  If you have a significant problem with obesity with a BMI of over 30 you still need to gain weight in a normal pregnancy but if you can limit it to 9kg with sensible diet and exercise you are doing all you can do to care for your pregnancy.

As far as caloric intake is concerned it has been shown in the first trimester there is no real need to increase your caloric intake. However, it is best to try and increase your intake in the second trimester by about 350 kcal-per day, and in the third trimester increase your caloric intake by 450 kcal-per day.  As far as actual nutrients themselves the average non-pregnant woman ingests 0.8g/kg per day of protein as a healthy protein intake and this should increase in pregnancy to 1.1g/kg per day.  This should be provided by a healthy diet, and protein powders and high protein drinks are to be avoided.  Carbohydrate intake in a normal non-pregnant woman should be in the order of 120 – 130 grams per day and in the normal healthy pregnancy this should increase to 175 grams per day.  This should be obtained by eating fruits, vegetable and whole grains and avoiding highly processed carbohydrates.  Trans-fatty acids should be avoided during pregnancy.

With respect to multivitamins and minerals a good prenatal vitamin complex usually contains everything that is needed. Therefore Elevit or Blackmores Pregnancy and Lactation Formula both contain similar formulas that are appropriate for use in pregnancy.

Vitamin B 12. Vegetarians and vegans should take additional vitamin B12 which is important for brain development in the developing fetus. 2.6mcg-per day is the recommended dose and this is the dose found in Elevit.

  • Folate. Try and commence folate in a good multivitamin at least one month prior to conception and continue taking a folate containing multivitamin until at least 12 weeks’ gestation. The recommended dose of folate to prevent fetal abnormalities such as neural tube defects is 0.4mg per day and Elevit contains 0.8mg in a single tablet, which is the recommended dose. If you have had a previous child with a neural tube defect, or you are diabetic or have a condition which interferes with folate absorption then take Megafol which is 5mg of folate per day.
  • B group vitamins. Multivitamins in pregnancy that are appropriate for pregnancy use contain a number of B group vitamins such as vitamin B3 and B 6 as well as vitamin B12. These vitamins are important as about 25% of pregnant women carry a single copy of a gene which can interfere with vitamin B metabolism. 
  • Vitamin D. Vitamin D deficiency is quite common in pregnancy. Normal levels of vitamin D are 50nmol/ltr. Women with a mild vitamin D deficiency of between 30 and 50 should be supplemented with 1000iu per day of vitamin D. Pregnant women with a more severe vitamin deficiency of less than 30nmol/ltr should take 2000iu per day. Vitamin D deficiency in the newborn can be associated with impaired skeletal development and it is important and this vitamin deficiency is addressed. Multivitamins such as Elevit contain only 200iu per tablet so an additional vitamin D supplement such as Ostelin containing 1000iu per table will need to be taken.
  • Calcium. The necessary daily intake of calcium in a pregnant woman is 1000mg per day. Adequate calcium intake has been shown to reduce the incidence of high blood pressure disorders in pregnancy and premature labour. Calcium is usually readily obtained through dairy products during pregnancy. However if the pregnant woman is intolerant or not able to intake dairy products it is best to use a calcium supplement containing 1000mg per tablet. Elevit only contains 125mg of calcium per tablet and an additional calcium supplement will therefore need to be provided.
  • Iron. Due to the demands of an increase in blood volume in the normal pregnant woman, and the demands placed by the developing fetus and placenta iron intake is important during pregnancy. Iron stores are always checked at the first antenatal visit and then again at 28 weeks’ gestation. If the iron stores are found to be low in a pregnant woman she should be given a supplement containing at least 60mg of iron per day. This is the amount in Elevit which is adequate for most pregnant woman. 
  • Iodine. Iodine intake is important in pregnancy to avoid an underactive thyroid gland which some pregnant women are prone to. Pregnant women should have at least 150mcg of iodine per day. An Elevit tablet contains 220mcg per day and is therefore sufficient.

All pregnant women will have their full blood count, iron stores, vitamin D levels and thyroid function checked in the first trimester. It is recommended that these levels be rechecked again at 28 weeks’ gestation to ensure adequate intake of essential vitamins and minerals.