Nutrition and Pregnancy

last authored:Oct 2014, Rebecca Green-LaPierre
last reviewed: Nov 2014, Syliva Blay




other articles: pre-natal visits    pregnancy

Healthy eating during pregnancy provides the nutrients and calories necessary to grow a healthy baby.  Oxygen and nutrients are passed from the maternal blood supply to the placenta, which in turns enters fetal-placental circulation to nourish the growing baby.  Eating well during pregnancy is beneficial for the mother too.  Being well-nourished lowers the mother’s chance of having health problems such as low iron, high blood glucose, or high blood pressure during pregnancy.  Healthful eating also helps the mother gain an appropriate amount of weight so the baby is a healthy size, increasing chances of a natural vaginal delivery.


This article will present recommendations for appropriate weight gain during pregnancy and then provide an approach to conducting a thorough nutritional assessment.  In discussing the nutrition management to promote a healthy pregnancy, the article will present five key beneficial nutrients a pregnant mother will want to ensure she is consuming enough of.  It will also note cautions on alcohol and caffeine consumption during pregnancy and present general food safety guidelines.  Finally, this article will highlight how to manage three conditions commonly experienced in pregnancy: heartburn, constipation and nausea and vomiting of pregnancy.

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Appropriate Weight Gain

The amount of weight a mother should gain during her pregnancy is based on her pre-pregnancy Body Mass Index (BMI).  BMI = weight (kg)/height(m)2.


Gaining a healthy amount of weight during pregnancy helps baby have a healthy start, reduces risk of complications in pregnancy and at delivery, and improves mother’s long-term health.


If a mother gains too little weight, there is increased risk of having a low birth weight baby, neonatal morbidities and mortalities, and developmental problems in the infant.  On the other side, too much weight gain during pregnancy puts the mother at risk for Gestational Diabetes, having a high birth weight baby, prolonged labour, birth trauma, caesarean section, as well as increased risk the baby will become overweight later in life and therefore at  higher risk for Type 2 Diabetes (IOM & NRC, 2009; Health Canada, 2010b).


The chart below displays current recommendations for weight gain during a normal, healthy pregnancy (IOM & NRC, 2009; Health Canada, 2010b). It is generally recommended short women aim for the lower end of the ranges, teenage women aim for the higher end of the ranges and when dealing with multipara (twins, triplets) the mother will need to gain more weight than shown here.



Recommended Total Weight Gain

Average Rate of Weight Gain in 2nd and 3rd Trimesters

< 18.5

12.5 - 18 kg (28 - 40 lb)

0.5 kg (1 lb)

18.5 - 24.9

11.5 - 16 kg (25 - 35 lb)

0.4 kg (1 lb)

25 - 29.9

7 - 11.5 kg (15 - 25 lb)

0.3 kg (0.6 lb)

> 30

5 - 9 kg (11-20 lb)

0.2 kg (0.5 lb)


A guideline to rate of weight gain during a normal healthy pregnancy sees a mother gaining 0-4 pounds total during her first trimester, and then (on average) 0.5-1.0 pounds each week during her second and third trimesters.


Pregnancy is often a very permissive time to eat liberally; however, pregnant women really only need to eat more calories in the second and third trimester.  Encourage women to incorporate two to three extra servings of healthy food into their meal and snack routine.  For example:

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Nutrition Assessment

When conducting routine antenatal care, it is imperative to assess the mother’s nutritional status to provide insight into reasons for inappropriate weight gain, sufficiency of key nutrients, food safety practices, and management of common pregnancy related issues.

  • History
  • Physical Exam
  • Lab Investigations


To assess the usual energy and nutrient intake of the patient conduct a Diet History.
Assess intake to determine patient’s usual dietary intake for food sources of folate, iron, omega 3, Calcium, Vitamin D as these are key nutrients pregnant mothers need to be adequate in.  Ask if mother took a folic acid supplement prior to conception and encourage mother to take a pre-natal supplement throughout the entire pregnancy. Ask about caffeine and alcohol intake.  


It is also wise to assess the mother’s ability to afford food and supplements, and to inquire how she accesses food (purchase at markets/stores, family garden, etc.) so you provide nutrition recommendations that can be implemented by the patient.


Assess if the patient has much control over what foods enter the house and are prepared (e.g. who does the procuring and preparation of meals?)


Determine if mother suffers from any co-morbidities that can be mitigated with diet therapy.

Physical Exam

Collect the mother’s height and pre-pregnancy weight to calculate pre-pregnancy BMI.  Weights should be collected at every prenatal visit to assess rate of gain and total weight gain to date.

Assess blood pressure.

Lab Investigations

Assess blood glucose to determine risk of gestational diabetes.

Assess hemoglobin and iron levels to determine risk of anemia.


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Nutrition Management for a Healthy Pregnancy

This section will discuss five key nutrients primary care providers want to ensure their mothers are getting enough of: folate, iron, omega 3 fatty acids, calcium and vitamin D; two nutrients mothers should be careful regarding their intake of: caffeine and alcohol; and food safety recommendations specific to pregnancy.


  • Folate
  • Iron
  • Omega 3
  • Calcium & Vitamin D
  • Caffeine
  • Alcohol
  • Food Safety


Folate is one of the B vitamins and is essential to the normal development of the fetus’ spine, brain and skull, especially during the first four weeks of pregnancy.  It is, therefore, important to start taking vitamin supplements with folic acid (synthetic form of folate) before one becomes pregnant to reduce the risk of neural tube defects. A daily prenatal multivitamin and mineral supplement that contains 0.4-0.6 mg of folic acid is generally recommended for healthy pregnancy women.  It should be noted the Tolerable Upper Level for folic acid is 1.0 mg and pregnant mothers are strongly advised to be aware of the folic acid content of supplements and/or fortified foods they are taking (Health Canada, 2010).


Excellent dietary sources of folate include mostly all dark green vegetables; legumes and whole grains are also sources.


Iron is necessary for red blood cells to deliver oxygen to both mother and fetus.  Mother’s blood supply experiences increased hemoglobin needs during pregnancy, so much so that dietary iron needs for a healthy woman increases from 18mg/day to 27mg/day (Health Canada, 2010).  It is critical that pregnant mothers consume adequate iron as this maternal dietary intake also provides the source of baby’s iron stores for first six months of their life outside the womb.


There are two types of dietary iron: heme and non-heme.  Heme iron is the most bioavailable type of iron and comes from animal products, the best dietary source being red meats.


Non-heme iron is less bioavailable and comes from plant sources including legumes, whole grains and dried fruit. Consuming foods rich in Vitamin C at the same time as eating non-heme iron containing foods will increase the body’s ability to absorb iron.  Foods rich in Vitamin C include oranges, tomatoes, red peppers, broccoli.


A prenatal multivitamin with 16-20 mg iron is generally recommended for healthy pregnant women.  Primary care providers should assess iron status during routine antenatal care bloodwork to assess if further supplementation is warranted.  It is recommended to take iron-rich supplements with Vitamin C and/or meat to increase absorption of iron.

Omega 3 Fatty Acids

Dietary needs for omega 3 fatty acids increase during pregnancy because of the their supportive role in the growth of baby’s brain and tissues.  Omega 3 fatty acids are considered an essential nutrient and therefore must be consumed from the diet. There are three types of omega-3 fatty acids in food: alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA).  Plant oils, specifically from flax, canola, walnut and soybean are good sources of ALA omega 3 fatty acids, as are walnuts, flax seed, chia seeds and hemp seeds.  Cold water fish are good sources of DHA and EPA omega 3 fats.

Calcium and Vitamin D

While neither calcium or Vitamin D requirements increase during pregnancy (Health Canada, 2010), many women do not eat enough of these nutrients (pregnant or not), thus potentially compromising bone growth and development in fetus and bone density in mother.


Dietary sources of calcium include dairy milk and dairy milk products, goats milk and goats milk products, dark green leafy vegetables (e.g. spinach, kale, bok choy) and salmon (with bones).
The most common source of vitamin D is from the sun. Vitamin D is not found naturally in many commonly consumed foods, with the only good natural dietary sources being certain kinds of fish and egg yolks.


The concerns about caffeine use during pregnancy are owing to the theoretical effects on the fetus as caffeine crosses the placental barrier, it is poorly metabolized by the fetus and caffeine's elimination half-life increases in late gestation.  Data about the consumption of caffeine doses of 300 mg/d or less do not suggest increased risk of adverse pregnancy, fertility, or neurodevelopmental outcomes.  At this time, the data about the risks of caffeine consumption of 300 mg/d or greater are limited and conflicting; therefore, it is best to limit caffeine intake to less than 300 mg/d (MotherRisk, 2013).


Common dietary sources of caffeine include coffee, black tea, green tea and cocoa.  Pregnant mothers and their health care providers should also be aware that a variety of medications also contain caffeine.


Women should be advised to abstain from alcohol during pregnancy. There are insufficient data to suggest a safe threshold for fetal alcohol exposure, thus there is no safe amount and no safe time to drink during pregnancy.  Alcohol crosses the placental barrier and can cause birth defects and brain damage to baby (Senikas et al., 2010).

Food Safety

During pregnancy the mother’s immune system is weakened making her more susceptible to food poisoning (also known as food-related illness, or foodborne illness).  Certain bacteria, viruses and parasites can cross the placenta putting baby at risk.  For example, pregnant women are 20 times more likely than other healthy adults to develop listeriosis if they are exposed to the Listeria bacteria (Government of Canada, 2014).


The following list provides an example of foods which are at higher risk to be contaminated by bacteria:

  • raw fish, especially shellfish such as oysters and clams
  • undercooked meat
  • undercooked poultry (meat should NOT be pink when cut into)
  • undercooked fish (fully cooked fish should flake when cut into)
  • raw or lightly cooked eggs
  • raw sprouts, especially alfalfa sprouts

Do not allow uncooked meat and its juices to contaminate other foods; for example prepare vegetables first and then use the knife and cutting board (or other surface) to cut the meat.  Be sure to thoroughly clean all utensils, cutting boards and other surfaces that have come into contact with uncooked meat with soap and hot water, or a bleach solution.


If access to refrigeration and food thermometers are available, temperature charts for food storage and cooking have been established by various governmental organizations including the USA and Canada.


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Nutrition Management for Common Issues During Pregnancy

The following three issues are experienced quite commonly during pregnancy, primary care provides should attempt to manage them via dietary interventions before introducing pharmaceuticals.


  • heartburn
  • constipation
  • nausea and vomiting of pregnancy

Heartburn/GERD/Acid Reflux

The expanding womb can put pressure on the stomach causing acidic stomach contents to back up into the esophagus. Dietary approaches to managing acid reflux, commonly called heartburn, include:

  • eat small, frequent meals, instead of a large meal at any given time
  • be aware of the common foods that can trigger reflux and avoiding them if necessary: citrus fruits, tomatoes, onions, garlic, spices, peppermint, chocolate, and caffeine
  • avoid high fat and greasy foods such as fatty cuts of meats, deep fried foods, foods smothered in butter or lard, foods made with lots of butter or lard (e.g. baked pies, pastries)

Other lifestyle approaches to managing reflux include:

  • remain upright for approximately an hour after eating
  • avoid eating two hours before bedtime
  • raise the head of the bed up using bricks or blocks, or use firm pillow to elevate the upper half of mother’s body
  • don’t wear clothing that is tight around the waist


Constipation is common in pregnancy for a variety of reasons including intestinal pressure from the growing uterus, hormonal changes affecting gut motility, and iron-rich prenatal vitamins and mineral supplements. Dietary approaches to managing constipation include:

  • drink minimum of two litres of water/day
  • choose a diet rich in high-fibre foods including legumes, whole grains, fruits and vegetables, nuts and seeds

Exercise and movement is very helpful in achieving regular bowel movement and it is important to remind mothers to respond quickly when they feel the urge to defecate.

Nausea and Vomiting of Pregnancy

main article: vomiting in pregnancy


NVP affects up to 85% of women, typically beginning between 4-9 weeks of pregnancy and is usually the most severe between 7-12 weeks.  For most women symptoms ease as they enter their second trimester (Koren & Maltepe, 2013). Dietary approaches to managing NVP include:

  • eating small, frequent meals,  instead of a large meal at any given time
  • avoid hunger or having an empty stomach; for example eat crackers/bread prior to rising out of bed in the morning
  • choose bland, lightly flavoured meals
  • eat foods cold or at room temperature
  • don’t eat and drink fluids at the same time, wait approximately 20 minutes after a meal to drink water, tea, etc. and when drinking fluids sip, do not gulp
  • choose high protein meals and snacks such as eggs, nuts and seeds, dairy and goat milk products, meats, fish, legumes.
  • try ginger root (e.g. grated in tea)
  • during the first trimester discontinue taking the iron-rich prenatal vitamin and mineral supplement and only take folic acid supplement. ensure by week 20 the mother is taking an iron-rich supplement again
  • a safe medication for NVP is Diclectin, which is a combination of doxylamine and vitamin B6

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Resources and References


Health Canada Pregnancy Weight Gain Calculator

WHO Reproductive Health Library  Antenatal Care - Nutrition during pregnancy


Government of Canada (2014). Food Safety for Pregnant Mothers. Retrieved from: Accessed Oct 27, 2014.


Health Canada (2010). Dietary Reference Intake Tables. Retrieved from: Accessed Oct 10, 2014.


Health Canada (2010b) Prenatal Nutrition Guidelines for Health Professionals: Gestational Weight Gain. ISBN: H164-126/2010E-PD  Available at


IOM (Institute of Medicine) and NRC (National Research Council). 2009. Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: The National Academies Press.


Koren & Maltepe (2013). How to Survive Morning Sickness Successfully.  Published by MotherRisk and Best Start.


MotherRisk. 2013. Is caffeine consumption safe during pregnancy? Retrieved from: Accessed Oct 14, 2014


Senikas et al (2010) Alcohol Use and Pregnancy Consensus Clinical Guidelines. Journal of Obstetrics and Gynecology Canada. 32 (8) Supplement 3. Available at:


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