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Pregnancy, first trimester: calorie and protein needs

For most of the first trimester your body is doing an enormous amount of organising and comparatively little building. That is why the energy increment published for this stage is so small that it disappears inside the error bars of any calculator — including this one.

These are population averages, not a plan for you. Energy and protein needs in pregnancy, first trimester are individualised by a midwife, doctor or registered dietitian who knows your history, your measurements and your blood work. Do not use this page to decide to eat more or less than you have been told to.

Pregnancy and afterWomenReference age 30

The first trimester is the stage where the gap between what people expect and what the reference values say is widest. "Eating for two" starts here in the popular imagination, but the additional energy requirement EFSA publishes for the first trimester is roughly 70 kcal a day. That is a slice of bread. It is smaller than the difference between two days of ordinary walking, and far smaller than the error in any prediction equation.

Meanwhile nausea, food aversions and a sudden dislike of foods you used to like can push intake the other way. If you are eating less than usual for a few weeks because of sickness, the reference values are not the thing to worry about — keeping fluids down and getting to your midwife appointments is. Weight can dip slightly in the first trimester and still be entirely unremarkable; only your clinician can say whether yours is.

The practical reading of this stage is: keep the pattern, not the arithmetic. The micronutrient side matters far more than the calorie side right now, because organogenesis is happening on a supply chain that was set up before you knew you were pregnant.

There is one more reason to be relaxed about the energy column and strict about everything else. Prediction equations were never validated in pregnancy. The tables further down this page apply an adult equation and an activity multiplier to a pregnant body, which is the standard approximation and still an approximation. Your maternity service works from measurements — weight trajectory, blood pressure, blood work and, later, fundal height and scans — and those beat any equation by a distance that is not close.

The adjustment for this stage

About +70 kcal a day on top of the pre-pregnancy requirement.

PAL 1.4 is the sedentary/low-activity level WHO/FAO and EFSA use for people with a desk job and little planned exercise.

Source: EFSA Dietary Reference Values — energy, protein and micronutrients (European Food Safety Authority) · checked 2026-09-02

The equation this page uses

BMR (men)   = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
BMR (women) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Daily target = BMR × 1.40 + 70

Worked through for the middle row of the table below: a woman of 70 kg and 168 cm at age 30 has a Mifflin-St Jeor BMR of about 1 439 kcal. Multiplied by PAL 1.40 that is 2 015 kcal, and adding the 70 kcal increment for this stage gives 2 085 kcal a day.

Worked example: by height and weight

Worked example: how age moves it

What changes if your activity is different

Protein for this stage

EFSA sets the adult population reference intake at 0.83 g of protein per kg of body weight a day and adds about 1 g a day in the first trimester — a rounding error next to normal day-to-day variation.

Source: EFSA Dietary Reference Values — energy, protein and micronutrients (European Food Safety Authority) · checked 2026-09-02

Your own numbers

The nutrients that matter most here

• Folate. Requirements rise sharply in early pregnancy. EFSA sets a higher reference intake for pregnant women than for other adults, and every EU country runs a folic-acid supplement programme around conception. Which product and which amount applies to you is a decision for your midwife or doctor, not for a web page.
• Iodine. Reference intakes go up in pregnancy because fetal thyroid development depends on the mother's supply. Dairy, white fish and iodised salt are the usual dietary carriers in Northern Europe.
• Iron. Blood volume starts expanding early. EFSA's reference intake for premenopausal women is already higher than for men, and pregnancy raises it further. Iron status is a blood test, not something you can read off a food diary.
• Vitamin D. Very few foods carry meaningful vitamin D, which is why EFSA publishes an adequate intake rather than a requirement, and why northern countries run winter supplement advice.
• Omega-3 (DHA). EFSA adds a DHA increment for pregnancy on top of the adult adequate intake for EPA plus DHA. Oily fish is the dietary route; national advice also limits certain species in pregnancy because of mercury.

Source: EFSA Dietary Reference Values — energy, protein and micronutrients (European Food Safety Authority) · checked 2026-09-02

Nutrient reference values are population figures. This page never tells you to take a supplement or how much of one to take — that is a decision for a clinician who can see your blood work and your medicines.

What to actually do

• Eat to appetite rather than to a target — the increment for this trimester is inside the noise of any estimate.
• Keep protein spread across the day rather than loaded into one meal, which is easier when nausea makes big meals unappealing.
• Follow your national food-safety list for pregnancy (soft cheeses, cured meats, certain fish); it is a safety rule, not a nutrition rule.
• Take the supplement your midwife or doctor prescribes on the schedule they set.

Frequently asked questions

Other life stages

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