Eating well in pregnancy: what actually changes

Written and evidence-checked by the VeriNourish Editorial Team against 7 named sources listed below. No licensed clinician reviews this content.

Pregnancy nutrition advice tends to arrive as two contradictory messages at once. Eat for two. Also, do not eat any of these forty things. Both are wrong in the same way: they treat pregnancy as a special diet rather than a normal one with a few specific adjustments.

Here is what actually changes, what the numbers are, and which of the warnings are worth taking seriously.

You need much less extra food than you think

The NHS puts it bluntly: eating for two is a myth. Extra calories are needed only in the final three months, and the figure is about 200 a day, which the NHS compares to two slices of wholemeal toast with spread (NHS).

US guidance sets the bar higher. The Institute of Medicine figures used in American practice add roughly 340 calories a day in the second trimester and 452 in the third (Med Clin North Am, 2016).

The two systems genuinely disagree, and it is worth knowing that rather than being handed one number as if it were settled. What they agree on is the shape: no extra calories at all in the first trimester, a modest addition later, and nothing resembling a second dinner.

Carrying twins or more is a different calculation. Energy and weight-gain targets in a multiple pregnancy are higher than the single-baby figures above, and they are set individually. Ask your midwife or obstetrician for your own numbers rather than applying anything on this page.

The nutrients that actually change, and by how much

Several reference intakes move in pregnancy. These are the ones most worth discussing at an appointment, using the US Dietary Reference Intakes for women aged 19 to 50.

Nutrient	Pregnancy RDA	Non-pregnant adult	Note
Folate	600 mcg DFE	400 mcg DFE	Neural tube closes in the first weeks
Iron	27 mg	18 mg	Blood volume rises sharply
Protein	71 g	46 g	Tissue growth
Calcium	1,000 mg	1,000 mg	Unchanged; absorption becomes more efficient

Figures from the Dietary Reference Intake tables. Pregnant teenagers have different targets, including 1,300 mg of calcium.

Two points the table cannot show. Folate is measured in dietary folate equivalents, which account for folic acid being absorbed more efficiently than food folate, so 600 mcg DFE of daily requirement and a 400 mcg folic acid supplement are not two versions of the same number and do not cancel each other out. And vitamin D targets differ by country and by whether you are counting total intake or a supplement: the UK advises a 10 microgram daily supplement in pregnancy (NHS), while the US RDA of 15 micrograms describes total intake from all sources and is not specific to pregnancy.

Iron deficiency is common in women of reproductive age, which is why our guide on iron in pregnancy exists separately.

Which supplements are actually advised?

Under UK guidance, two: folic acid at 400 micrograms daily through the first 12 weeks, and vitamin D at 10 micrograms daily from October to March, considered year-round if you cover most of your skin outdoors, are mostly indoors, or have darker skin. Start folic acid before conception if you can, and if you did not, start as soon as you know you are pregnant. A prescribed 5 mg folic acid dose applies to specific groups, including diabetes, a previous pregnancy affected by a neural tube defect or a family history of one, sickle cell anemia or thalassemia, and some epilepsy or HIV medication. That higher dose is prescribed, and the list here is a summary rather than the full criteria (NHS).

Iron is where guidance diverges, so this depends on where you are cared for. UK practice adds iron when blood tests show it is needed rather than by default, partly because unnecessary iron commonly causes constipation and nausea. The WHO recommendation is different: daily oral supplementation with 30 to 60 mg of elemental iron alongside 400 micrograms of folic acid for pregnant women, to prevent maternal anemia, low birth weight and preterm birth (WHO, 2025).

Neither position makes the other wrong, and neither is a reason to change what you are already taking. If iron has been prescribed for you, keep taking it as directed and raise any side effects with your midwife rather than stopping.

One supplement to actively avoid: anything containing vitamin A as retinol, including cod liver oil. High vitamin A can harm a developing baby, which is also why liver is off the menu (NHS).

Our prenatal vitamins guide covers which forms are worth paying for and which are marketing, and folate explains the difference between folate and folic acid.

The food list, sorted by how much it matters

Not every warning carries equal weight. These are grouped by what is actually being avoided.

Listeria risk, so avoid or cook thoroughly:

Mold-ripened soft cheeses: brie, camembert, chèvre
Soft blue cheeses: Danish blue, gorgonzola, roquefort
Unpasteurized milk, cream, yogurt, butter and ice cream

Cooked until steaming hot, the soft cheeses are fine. Hard cheeses are allowed under UK guidance even when made with unpasteurized milk, which is a point where advice differs between countries; if you are cared for outside the UK, follow the local rule.

Toxoplasmosis and other infection risk:

Raw or undercooked meat
Raw fish and raw shellfish, including sushi made with raw fish
Cold-smoked or cured fish such as smoked salmon and gravlax, and cooked cold prawns, unless heated until steaming hot
Wash fruit, vegetables and salad thoroughly to remove soil

Lead from shot, so avoided for a different reason: game meats such as goose, partridge, pheasant and venison are on the NHS avoid list because of possible lead from shot. Cooking does not address lead, which is why this sits apart from the infection group (NHS).

Mercury, so avoid entirely: shark, swordfish and marlin.

Vitamin A, so avoid entirely: liver and liver products.

Limits rather than bans, as set by UK guidance:

Caffeine: no more than 200 mg a day
Oily fish: no more than 2 portions a week
Tuna: no more than 4 cans or 2 tuna steaks a week
Herbal tea: no more than 4 cups a day, and avoid any containing liquorice root

All of the above from NHS. Alcohol is the one item with no safe threshold given: the advice is none.

Fish is a food to eat, not only to fear

The mercury warnings get repeated so often that plenty of women drop fish entirely, which is the opposite of the advice.

Two portions a week is the target, one of them oily, such as salmon or sardines (NHS). The two limits exist for different reasons: the cap on oily fish is about pollutants that build up in the fish over time, while the tuna limit is about mercury specifically.

Three species are off the list entirely for mercury. These portions are UK figures; other countries set them differently.

The rest of the plate

The ordinary advice does not change much, which is the point.

Five portions of fruit and vegetables a day. Starchy foods as the base of meals: bread, potatoes, rice, pasta. Protein at every meal from meat other than liver, fish, poultry, eggs, beans, pulses and nuts. Dairy, or fortified alternatives if you avoid dairy, for calcium (NHS).

In practice a day might look like porridge made with milk or a fortified alternative with fruit, a jacket potato with beans and salad, and a salmon fillet with rice and vegetables, with yogurt or nuts between. That covers protein at each meal, one oily fish portion, and calcium without anything specialized.

On eggs, UK guidance distinguishes by stamp: British Lion or Laid in Britain eggs can be eaten raw or runny, while other eggs should be cooked until white and yolk are solid (NHS).

Our protein guide covers how to spread protein across meals, and iron-rich foods covers getting iron from food rather than a tablet. Our protein calculator has no pregnancy setting, so its number is a general adult estimate; use the 71 g figure above and your midwife's advice instead.

When eating well is not the problem

Nausea in the first trimester makes most of this advice academic. Mild to moderate nausea that lets you keep fluids down is common and usually settles. Keep taking folic acid, eat what stays down, and read our guide on morning sickness for what helps.

Severe vomiting is a different situation and needs treatment rather than diet advice. Contact your midwife or maternity unit the same day if you cannot keep any fluids down, if you are passing very little or very dark urine, if you feel dizzy on standing, or if you are losing weight. Untreated, this can lead to dehydration.

Speak to your midwife or doctor rather than adjusting your diet alone if:

You have lost weight, or your appetite has not recovered
You have been told your iron or ferritin is low
You have gestational diabetes or a previous pregnancy affected by it
You follow a vegan diet, which needs B12 and often iodine attention
You have a condition affecting absorption, such as celiac disease or inflammatory bowel disease

This is general information, not a personalized plan. Your midwife knows your bloods, your history and your weight trajectory, and none of those are visible from here.

Frequently asked questions

How many extra calories do I need in pregnancy?

Far fewer than most people assume. UK guidance is about 200 extra calories a day, and only in the final three months. US guidance is higher, at roughly 340 a day in the second trimester and 450 in the third. Neither comes close to eating for two. If you are carrying twins or more, the targets are higher and are set individually, so ask your maternity team for your own numbers.

Do I have to give up coffee?

No, but UK guidance keeps it under 200 mg of caffeine a day. That is roughly two mugs of instant coffee, or one mug of filter coffee. Tea, cola, energy drinks and chocolate all count toward the total.

Which cheeses are actually off the list?

Mold-ripened soft cheeses like brie, camembert and chèvre, and soft blue cheeses like gorgonzola and roquefort, unless they are cooked until steaming hot. Under UK guidance hard cheeses are fine, including those made with unpasteurized milk, while unpasteurized milk, cream, yogurt, butter and ice cream are not. Other countries advise more cautiously, so follow the guidance where you are cared for.

Do I need a prenatal vitamin, or is food enough?

UK guidance advises two supplements regardless of diet: 400 micrograms of folic acid, ideally started before conception and continued through the first 12 weeks, and 10 micrograms of vitamin D from October to March, or year-round for some groups. If you did not start folic acid before conceiving, begin as soon as you know. Iron differs by country: UK practice adds it when blood tests show it is needed, while WHO recommends routine daily iron with folic acid in pregnancy. Follow the advice of the team caring for you, and do not stop iron that has been prescribed.

Is fish safe in pregnancy?

Most of it, and it is worth eating. UK guidance is two portions of fish a week, one of them oily, with no more than two oily portions weekly and tuna capped at four cans or two steaks. Shark, swordfish and marlin are avoided entirely for mercury. Cold-smoked and cured fish, and cooked cold prawns, should be heated until steaming hot.