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Nutrition and pregnancy

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Pregnant woman eating fruit.

Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy.

In a precursory study into the link between nutrition and pregnancy in 1950 women who consumed minimal amounts over the eight week period had a higher mortality or disorder rate concerning their offspring than women who ate regularly, because children born to well-fed mothers had less restriction within the womb.[1]

Not only have physical disorders been linked with poor nutrition before and during pregnancy, but neurological disorders and handicaps are a risk that is run by mothers who are malnourished, a condition which can also lead to the child becoming more susceptible to later degenerative disease(s).[2]. 23.8% of babies are estimated to be born with lower than optimal weights at birth due to lack of proper nutrition.[3]


The following sections refer to the pertinence of nutrition throughout pregnancy, and are thoroughly researched enough to be usable for mothers or couples planning on conceiving.

Nutrition before pregnancy

Potentially harmful pre-pregnancy determinants

It is known that good nutrition before pregnancy is important because of the amount of "resources" childbirth requires. The process of pre-pregnancy nutrition is a process of "building up" the immune system in preparation of pregnancy, and is known as being one of the major factors in determining the success rate of conceiving healthy children.

There are foods that may decrease your fertility such as high mercury fish, foods that contain trans fat, and consuming too much caffeine. High levels of mercury in the body can cause challenges with fertility and it can be harmful to the developing fetus. Some high mercury fish to avoid may include swordfish, mackerel, and shark. Trans fat can also be very harmful to fertility. The more trans fat in a woman's diet, the higher her chances of developing ovulatory infertility. Trans fats are found in processed and fried foods that include packaged foods, french fries, donuts, and margarine. Too much caffeine, such as three or more cups a day, can lower fertility and increase the rate of miscarriage.[4]

As with most situations, the most important factor in pre-pregnancy nutrition is ensuring that the mother is healthy and without any major factors which could worsen the chances of conceiving, factors such as anorexia or bulimia are thought to be direct links with infertility; the minimum body mass index for conceiving mothers being 20.8. Gaining weight restores fertility and a body fat content of at least 22% is necessary for normal ovulatory function and menstruation.[5]

This is also seen to be true with obese women with a BMI above 30 which is a direct result of decrementing amounts of insulin activity and sex hormones may reduce the viability of the ovum.

If a woman wishing to conceive needs to gain or lose weight, it is recommended that you do so gradually, changing no more than 1 to 2 lbs/week.[6] The ideal range of weight for women wishing to conceive children is thought to be optimal at body mass indexes between 20 and 26. If this, again, is used in conjunction with good nutrition and diet before pregnancy in terms of a normal balanced diet, then reserves of micronutrients, providing materials for pregnancy, would also be maximised.[2]

For more information on how BMI is calculated, please refer to the body mass index article.

Beneficial pre-pregnancy nutrients

As with most diets, there are chances of over-supplementing, however, as general advice, both state and medical recommendations are that mothers follow instructions listed on particular vitamin packaging as to the correct or recommended daily allowance (RDA).

  • Magnesium and zinc supplementation for the binding of hormones at their receptor sites.
  • Folic acid supplementation, or dietary requirement of foods containing it for the regular growth of the follicle.
  • Regular Vitamin D supplementation decreases the chances of deficiencies in adolescence. More importantly, it is known to reduce the likelihood of rickets with pelvic malformations which make normal delivery impossible.
  • Regular Vitamin B12 supplementation, again is known to reduce the chances of infertility and ill health.
  • Omega-3 fatty acids can increase blood flow to reproductive organs and may help regulate reproductive hormones.[4] Consumption is also known to help prevent premature delivery and low birth weight.[5] The best dietary source of omega-3 fatty acids is oily fish. Some other omega-3 fatty acids not found in fish can be found in foods such as flaxseeds, walnuts, pumpkin seeds, and enriched eggs.[4]

Nutrition during pregnancy

The conception and the subsequent weeks afterwards is the time when it is at its most vulnerable, as it is the time when the organs and systems develop within. The energy used to create these systems comes from the energy and nutrients in the mother's circulation, and around the lining of the womb, such is the reason why correct nutrient intake during pregnancy is so important.

During the early stages of pregnancy, the placenta is not formed yet, so there is no mechanism to protect the embryo from the deficiencies which may be inherent in the mother's circulation, so it is critical that the correct amount of nutrients and energy are consumed. Supplement your diet with foods that are rich in folic acid, like orange and dark green leafy vegetables to prevent neural tube birth defects in your baby. Taking iron-rich foods like lean red meat and beans helps to prevent anemia and ensure adequate oxygen for your baby.[7]

Potentially harmful determinants during pregnancy

It is advised for pregnant women to pay special attention to food hygiene during pregnancy in addition to avoiding certain foods in order to reduce the risk of exposure to substances that may be harmful to the developing fetus. This can include food pathogens and toxic food components, alcohol, and dietary supplements such as vitamin A.[5]

Dietary vitamin A is obtained in two forms which contain the preformed vitamin (retinol), that can be found in some animal products such as liver and fish liver oils, and as a vitamin A precursor in the form of carotenes, which can be found in many fruits and vegetables.[5] Intake of retinol, in extreme cases, has been linked to birth defects and abnormalities. However, regular intake of retinol is not seen as dangerous. It is noted that a 100 g serving of liver may contain a large amount of retinol, so it is best that it is not eaten daily during pregnancy, something which is also the same with alcohol intake in binge drinking.

Excessive amounts of alcohol have been proven to cause Fetal alcohol syndrome. The World Health Organization recommends that alcohol should be avoided entirely during pregnancy, given the relatively unknown effects of even small amounts of alcohol during pregnancy.[8]

Pregnant women are advised to pay particular attention to food hygiene and to avoid certain foods during pregnancy in order to minimize the risk of food poisoning from potentially harmful pathogens such as listeria, taxoplasmosis, and salmonella. Pregnant women are therefore advised to avoid foods in which high levels of the bacteria have been found, such as in soft cheeses. Listeria are destroyed by heat and therefore pregnant women are advised to reheat ready-prepared meals thoroughly. Pregnant women should also wash their fruit and vegetables very thoroughly in order to minimize risk. Salmonella poisoning is most likely to come from raw eggs or undercooked poultry.[5] Maternal obesity has a significant impact on maternal metabolism and offspring development.[9] Insulin resistance, glucose homeostasis, fat oxidation and amino acid synthesis are all disrupted by maternal obesity and contribute to adverse outcomes.[9] Modification of lifestyle is an effective intervention strategy for improvement of maternal metabolism and the prevention of adverse outcomes.[9]

Nutrient Recommendation (Extra = Above RDA) Maximum/Total amount
Energy Increase by 200 kcal (840 kJ) per day in last trimester only. RDA
Proteins Extra 6 g per day 51 g per day
Thiamin Increase in line with energy; increase by 0.1 mg per day 0.9 mg per day
Riboflavin Needed for tissue growth; extra 0.3 mg per day 1.4 mg per day
Niacin Regular supplementation/diet of substance. No increase required. RDA
Folate Maintain plasma levels; extra 100 µg per day 300 µg per day
Vitamin C Replenish drained maternal stores; extra 120 mg per day 50 mg per day
Vitamin D Replenish plasma levels of vitamin 10 µg per day. RDA
Calcium Needs no increase RDA
Iron Extra 3 mg per day needed RDA
Magnesium, zinc, and copper Normal supplementation or consumption. RDA
Iodine Extra 100 µg per day. 250 µg per day[10][11][12][13]

Folate

Folic acid, which is the synthetic form of the vitamin folate, is extremely critical both in pre-and peri-conception.[5] Deficiencies in folic acid may cause neural tube defects; women who had 4 mg of folic acid in their systems due to supplementing 3 months before childbirth significantly reduced the risk of NTD within the fetus. This is now advocated by the UK department of health, recommending 400 µg per day of folic acid.

The development of every human cell is dependent on an adequate supply of folic acid. Folic acid governs the synthesis of the precursors of DNA, which is the nucleic acid that gives each cell life and character. Folic acid deficiency results in defective cellular growth and the effects are most obvious on those tissues which grow most rapidly.[14]

Folate and Acute Lymphoblastic Leukemia

Along with neural tube development, folate affects DNA synthesis in multiple ways. As Ball explains, folate is involved in the construction of purines and pyrimidines, the building blocks of nucleic acids.[15] Folate is also necessary to make s-adenosylmethionine (SAM), which acts as a methyl donor in the synthesis of DNA.[15] Because of its role in these important mechanisms, fetal DNA would be significantly altered if a maternal folate deficiency is present. One possible outcome is DNA mutation, which could prevent normal gene expression. For example, a tumor-suppressing gene might be turned off, altering normal immune function in preventing cancer growth.[15] Thompson et al.[16] examined the relationship between maternal supplementation of folate and iron during pregnancy and incidences of acute lymphoblastic leukemia (ALL) in their children. Increased rates of ALL were found in children whose mothers did not take iron and folate supplements. Iron alone did not seem to reduce the risk of developing ALL, however iron in combination with folate was shown to have a protective effect in decreasing the risk for ALL. Thompson and his associates (2001), concluded that maternal folate supplementation throughout pregnancy plays an important role in reducing the risk for childhood ALL.[16]

Nutrition after pregnancy

Proper nutrition is important after delivery to help the mother recover, and to provide enough food energy and nutrients for a woman to breastfeed her child. Women having serum ferritin <= 70 µg/L may need iron supplements to prevent iron deficiency anaemia during pregnancy and postpartum.[17][18]

References

  1. ^ Rasmussen, K. M., (1992) The influence of maternal nutrition on lactation . Annual review of Nutrition 12, p103-117
  2. ^ a b Barasi, E. M., (2003) Human Nutrition - A Health Perspective . London : Arnold Publishing (ISBN 0340810254)
  3. ^ "WHO | 10 facts on nutrition". Who.int. 2011-03-15. Retrieved 2011-08-07.
  4. ^ a b c Murkoff, Heidi (May, 20 2010). "Foods that make you fertile". Everyday Health. Retrieved 2010-11-30. {{cite web}}: Check date values in: |date= (help)
  5. ^ a b c d e f Williamson CS (2006). "Nutrition in pregnancy". British Nutrition Foundation. 31: 28–59.
  6. ^ Kolasa KM, Weismiller DG (2008). "13. Nutrition during Pregnancy and Lactation". In Berdanier CD, Dwyer J, Feldman EB (ed.). Handbook of Nutrition and Food, Second Edition. Boca Raton: CRC/Taylor & Francis.{{cite book}}: CS1 maint: multiple names: editors list (link)
  7. ^ "Pregnancy Diet Plan". Retrieved April 22, 2011.
  8. ^ World Health Organisation Framework for alcohol policy in the WHO European Region
  9. ^ a b c Nelson SM, Matthews P, Poston L (2010). "Maternal metabolism and obesity: modifiable determinants of pregnancy outcome". Hum. Reprod. Update. 16 (3): 255–75. doi:10.1093/humupd/dmp050. PMC 2849703. PMID 19966268.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Zimmermann MB (2007). "The adverse effects of mild-to-moderate iodine deficiency during pregnancy and childhood: a review". Thyroid. 17 (9): 829–35. doi:10.1089/thy.2007.0108. PMID 17956157.
  11. ^ Pérez-López FR (2007). "Iodine and thyroid hormones during pregnancy and postpartum". Gynecol. Endocrinol. 23 (7): 414–28. doi:10.1080/09513590701464092. PMID 17701774.
  12. ^ Glinoer D (2007). "Clinical and biological consequences of iodine deficiency during pregnancy". Endocr Dev. 10: 62–85. doi:10.1159/000106820. PMID 17684390.
  13. ^ Sethi V, Kapil U (2004). "Iodine deficiency and development of brain". Indian J Pediatr. 71 (4): 325–9. doi:10.1007/BF02724099. PMID 15107513.
  14. ^ Hibbard BM (1964). "The role of folic acid in pregnancy". An International Journal of Obstetrics and Gynaecology. 71 (4): 529–42. doi:10.1111/j.1471-0528.1964.tb04317.x. {{cite journal}}: Unknown parameter |month= ignored (help)
  15. ^ a b c Ball, G.F.M., (2004) "Vitamins: Their Role in the Human Body" London: Blackwell Publishing
  16. ^ a b Thompson, J.R, Fitz Gerald, P., Willoughby, M.L.N., & Armstrong, B.K. (2001). "Maternal folate supplementation in pregnancy and protection against acute lymphoblastic leukaemia in childhood". Lancet. 358 (9297): 1935–1940. doi:10.1016/S0140-6736(01)06959-8. PMID 11747917.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Milman N, Byg KE, Bergholt T, Eriksen L, Hvas AM (2006). "Body iron and individual iron prophylaxis in pregnancy--should the iron dose be adjusted according to serum ferritin?". Ann. Hematol. 85 (9): 567–73. doi:10.1007/s00277-006-0141-1. PMID 16733739.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. ^ Milman N, Bergholt T, Eriksen L; et al. (2005). "Iron prophylaxis during pregnancy -- how much iron is needed? A randomized dose- response study of 20-80 mg ferrous iron daily in pregnant women". Acta Obstet Gynecol Scand. 84 (3): 238–47. doi:10.1111/j.0001-6349.2005.00610.x. PMID 15715531. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  • UK Department of Health (1991) Dietary reference values for food energy and nutrients for the United Kingdom. - Report on Health and social Subjects No 41. report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy London:HMSO
  • Health Education Authority (1996) Folic acid - what all women should know (leaflet) London:HEA

Further reading

Healthy eating during pregnancy - What to eat, what not to eat and why

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