When you’re preparing for pregnancy, or already expecting, nutrition often becomes a bigger focus. Prenatal vitamins are designed to supplement the diet. They provide specific vitamins and minerals that are commonly recommended during this life stage.
A varied, balanced diet is the foundation of good health, but some people also use prenatal supplements to support nutrient intake. Nutritionist Helen Roach explains how these supplements fit into overall preconception and pregnancy nutrition, following UK guidance.
What are prenatal vitamins
Prenatal vitamins are vitamins and mineral supplements formulated for people women who are either trying to conceive, are pregnant or breastfeeding.
They are not a substitute for a varied diet and healthy lifestyle. They can help people maintain adequate intake of nutrients that may be harder to get from food alone, such as folic acid and vitamin D.
Prenatal supplements are designed to reflect nutritional recommendations specific to pregnancy. So, they often differ from standard multivitamins in both nutrient selection and dosage.
When should you start taking prenatal vitamins?
Many healthcare professionals suggest considering a prenatal supplement before conception, often around three months prior to trying for a baby.
This is because certain nutrients, particularly folic acid, are important very early in pregnancy, sometimes before pregnancy is confirmed. The NHS recommends that women who are planning a pregnancy take 400 micrograms (µg) of folic acid daily. Starting before conception and continuing through the first 12 weeks of pregnancy 1
Other nutrients often found in prenatal supplements, like vitamin D, iodine and iron, help support the body’s increased nutritional needs during pregnancy.
Key nutrients commonly found in prenatal vitamins
Folic acid (folate)
Folate is the natural form of vitamin B9 found in foods such as leafy green vegetables, legumes, and citrus fruits. Folic acid is a synthetic form used in supplements and fortified foods.
Folic acid contributes to normal maternal tissue growth during pregnancy. It plays a role in the early development of the baby’s neural tube, which forms the brain and spinal cord. Because this process occurs in the first few weeks of pregnancy, adequate intake before conception is important.
The NHS recommends 400 µg of folic acid daily for at least one month before and until 12 weeks of pregnancy 1
Vitamin D
Vitamin D helps maintain normal bones and teeth and supports the normal function of the immune system. During pregnancy, vitamin D & Calcium are needed for normal growth and development of bone in children. This applies only to Vitamin D > 0.75 µg (15% NRV per daily dose) and Calcium >120 mg (15% NRV per daily dose).
In the UK, most vitamin D comes from sunlight. From September to March, the NHS recommends that everyone in the UK, including those planning a pregnancy or who are pregnant, take a daily supplement of 10 micrograms (µg).2/span>
Iron
Iron contributes to the formation of red blood cells and the transport of oxygen around the body (haemoglobin). During pregnancy, iron requirements increase to support the growing baby and placenta.
Iron is found in foods such as red meat, poultry, fish, eggs, leafy green vegetables, and pulses. Some people may find it difficult to meet increased iron needs through diet, alone. This is why it is often included in prenatal supplements.
Iodine
Iodine contributes to normal thyroid function and normal cognitive development. During pregnancy, iodine supports the production of thyroid hormones. These are important for the baby’s growth and development.
Dietary sources include dairy products, eggs, seafood, and some fortified plant-based alternatives. Data from the National Diet and Nutrition Survey, suggests that mild to moderate iodine insufficiency is common among women of childbearing age in the UK 3
Calcium
Calcium contributes to the maintenance of normal bones and teeth. During pregnancy, calcium supports the development of the baby’s bones and teeth.
If dietary intake is low, calcium may be drawn from maternal bone stores. Calcium is found in dairy products, fortified plant milks, leafy green vegetables, and nuts such as almonds.
Omega-3 fatty acids (DHA and EPA)
Docosahexaenoic acid (DHA) and eicosatetraenoic acid (EPA) are omega-3 fatty acids obtained from diet or supplements. DHA maternal intake contributes to the normal eye and brain* development of the foetus and breastfed infants.
Oily fish such as salmon, sardines and mackerel are primary dietary sources. NHS guidance recommends limiting certain fish during pregnancy due to mercury content 4
* Beneficial effect is obtained with a daily intake of 200 mg of DHA in addition to the recommended daily intake for omega-3 fatty acids for adults, i.e. 250 mg DHA and EPA.
Vitamin B12
Vitamin B12 contributes to normal red blood cell formation and works alongside folate in normal cell division.
It is found mainly in animal-derived foods such as meat, fish, eggs, and dairy. People following a vegetarian or vegan diet may get less vitamin B12 from food and might want to talk to a healthcare professional about supplements.
Magnesium
Magnesium contributes to normal muscle function, energy-yielding metabolism, and the reduction of tiredness and fatigue.
It is found in foods such as nuts, seeds, wholegrains, legumes, leafy green vegetables, and dark chocolate. Magnesium supports various body functions and may be included in prenatal supplements to contribute to overall nutrient intake.
Frequently asked questions
What’s the difference between prenatal and regular multivitamins?
Prenatal supplements are formulated specifically for pregnancy and preconception, providing nutrients such as folic acid, vitamin D and iodine in amounts aligned with UK guidance.
Standard multivitamins are designed for the general adult population and may not provide sufficient amounts of certain pregnancy-specific nutrients. Some may also contain vitamin A (retinol), which should be avoided during pregnancy.
Always check labels and choose supplements that align with NICE and NHS guidance 5
What if you forget to take your prenatal vitamins?
Missing a day or two is unlikely to cause harm. However, it’s important not to double up doses to compensate, as this could lead to excessive intake of some nutrients.
Prenatal supplements are designed to be taken consistently and as directed.
What if you weren’t taking prenatal vitamins before finding out you’re pregnant?
If you discover you're unexpectedly pregnant, beginning a prenatal supplement early can help support important nutrients, alongside eating a balanced diet.
Do prenatal vitamins balance hormones?
Prenatal vitamins are not a treatment for hormonal imbalance. However, they provide nutrients that contribute to overall nutritional status, which supports general health during preconception and pregnancy.
They should be viewed as one part of a wider wellbeing approach that includes diet, movement, sleep, and stress management.
When to speak to a healthcare professional
Nutritional needs vary between individuals and may be influenced by factors such as age, medical conditions, medications, dietary patterns or previous contraceptive use.
If you’re unsure whether a prenatal supplement is right for you, or if you have specific concerns about nutrients such as iron, iodine, or vitamin D, it’s always advisable to speak with your GP, midwife, or pharmacist.
References
1. NHS. Vitamins, minerals and supplements in pregnancy.
2. NHS. Vitamin D.
3. National Diet and Nutrition Survey. Iodine intake in women of childbearing age.
4. NHS. Foods to avoid in pregnancy.
5. NICE. Antenatal care guidelines.
6. EFSA. Dietary Reference Values for nutrients.
