Macronutrient needs during pregnancy shift meaningfully from pre-pregnancy baselines, and the changes are not as simple as “eat more of everything.” Protein requirements rise substantially, especially in later pregnancy. Carbohydrate needs are shaped by the glucose demands of the placenta and fetal brain. Fat quality matters more than fat quantity, with certain long-chain fatty acids playing outsized roles in fetal neurological development. How these three macronutrients balance against each other depends on factors like gestational stage, whether you’re carrying multiples, and whether gestational diabetes enters the picture.
How Many Extra Calories You Actually Need
The old advice to “eat for two” overstates it. Your basal metabolic rate does climb throughout pregnancy, but the increase is gradual: roughly 10 to 11 extra calories burned per week of gestation on average.1The American Journal of Clinical Nutrition. Energy requirements during pregnancy based on total energy expenditure and energy deposition That adds up to meaningful extra energy needs by the third trimester, but in early pregnancy the additional demand is modest. Total energy expenditure rises more slowly than basal metabolism would suggest, because most people scale back physical activity somewhat as pregnancy progresses.
The way extra calories distribute across trimesters matters. Estimates based on basal metabolic rate and those based on total energy expenditure agree on the overall number for a full pregnancy but disagree on the trimester breakdown.2PubMed. Energy metabolism during human pregnancy First trimester needs are small enough that many people do not need to deliberately eat more. Second trimester adds roughly 300 to 350 extra calories per day. Third trimester adds somewhat more, around 400 to 500. These are ballpark ranges, not precision targets. Your body’s hunger signals are often a better guide than rigid calorie counting during an uncomplicated pregnancy.
Protein Requirements Are Higher Than Most Guidelines Say
This is where the research has moved ahead of mainstream advice. Standard dietary guidelines for pregnancy typically recommend around 0.88 to 1.1 grams of protein per kilogram of body weight per day. Newer experimental work using amino acid oxidation methods found that actual requirements are closer to 1.2 grams per kilogram per day in early pregnancy (around 16 weeks) and 1.52 grams per kilogram per day in late pregnancy (around 36 weeks).3PubMed Central. Protein and Amino Acid Requirements during Pregnancy For someone weighing 70 kilograms, that translates to about 84 grams of protein daily in early pregnancy and roughly 106 grams in late pregnancy.
The experimental data supporting these higher estimates identified clear breakpoints where adding more protein stopped improving how efficiently the body used amino acids for building new tissue.4The Journal of Nutrition. Protein Requirements of Healthy Pregnant Women during Early and Late Gestation Are Higher than Current Recommendations Below these breakpoints, the body was not getting enough amino acids to keep up with the demands of a growing fetus, expanding blood volume, and new placental tissue. Above them, excess protein was simply oxidized for energy rather than used for tissue building.
Where your protein comes from appears to matter. In a large study of Chinese pregnant women who had low overall protein intake, each small increase in the share of calories from animal protein and dairy protein was linked to higher birth weights and lower odds of low birth weight, small-for-gestational-age babies, and intrauterine growth restriction.5PubMed Central. Dietary protein intake during pregnancy and birth weight among Chinese pregnant women with low intake of protein Plant protein showed no such association in that population. This does not mean plant protein is useless, but it does suggest that animal sources provide a more complete amino acid profile that supports fetal growth more efficiently, which is worth knowing if your diet is largely plant-based.
The Upper Limit Problem With Protein
Before you start piling on the chicken breast, there is an important caveat. A review of controlled clinical trials found that high-protein supplementation during pregnancy did not benefit mother or infant and may actually impair fetal growth.6The American Journal of Clinical Nutrition. Effects of energy and protein intakes on pregnancy outcome: an overview of the research evidence from controlled clinical trials The concern here is not protein itself but what happens when protein intake gets so high that it displaces other macronutrients or pushes total calorie intake into territory the body handles poorly. Very high protein diets tend to crowd out carbohydrates, and as we’ll see, the fetus and placenta have independent glucose requirements that cannot be met by protein alone.
A study comparing a high-protein, low-glycemic-index diet during pregnancy to a more moderate approach found no meaningful differences in offspring growth or obesity risk from birth through age 18 once the data were properly adjusted for multiple comparisons.7European Journal of Clinical Nutrition. Association of a high-protein and low-glycemic-index diet during pregnancy with offspring growth and obesity until the age of 18 years – a target trial emulation So pushing protein higher than you need does not seem to produce better outcomes, and going too high may produce worse ones. The sweet spot is meeting the elevated requirements without going overboard.
Carbohydrates Feed the Placenta, Not Just the Baby
Carbohydrates get a complicated reputation during pregnancy, partly because of the fear of gestational diabetes. But the placenta itself runs primarily on glucose. It is as dependent on maternal blood glucose as the brain is. A 2023 analysis re-examined the estimated average requirement for carbohydrates during pregnancy and calculated that the placenta alone consumes about 36 grams of glucose per day.8PubMed Central. Re-examination of the estimated average requirement for carbohydrate intake during pregnancy: Addition of placental glucose consumption Adding together the glucose needs of the maternal brain (about 100 grams per day), the fetal brain (about 35 grams per day), and the placenta brings the proposed recommended dietary allowance to 220 grams of carbohydrate per day.
That 220-gram figure is worth sitting with, because many popular macro-tracking approaches for non-pregnant adults run well below it. If you were eating 150 grams of carbs daily before pregnancy, you would need to rethink that number. The fetal brain and placenta do not have the metabolic flexibility that adult muscles do; they need glucose specifically, and they need it continuously.
When Carbs Need to Be Managed More Carefully
For the roughly 6 to 9 percent of pregnancies affected by gestational diabetes, the macro picture shifts. One trial found that restricting carbohydrates to under 42 percent of total energy improved blood sugar control, reduced the need for insulin, and lowered the rate of oversized babies compared to a higher-carb approach.9The American Journal of Clinical Nutrition. Carbohydrate and lipid metabolism in pregnancy: normal compared with gestational diabetes mellitus That sounds like a vote for low-carb eating in gestational diabetes, and to some extent it is, but the evidence has limits.
A review examining the question of how low carbohydrate intake can go in pregnancy found that evidence from multiple reports supports a carbohydrate range of 47 to 70 percent of energy for normal fetal growth, which is actually higher than many low-carb thresholds people are familiar with. Intakes below 175 grams of carbohydrate per day have unclear effects on maternal ketone levels and blood lipids. A recent trial also found a higher risk of micronutrient deficiency when carbohydrates dropped to 165 grams or less per day in women with gestational diabetes.10PubMed Central. The Carbohydrate Threshold in Pregnancy and Gestational Diabetes: How Low Can We Go? The practical takeaway: if you have gestational diabetes, your carb intake may need to come down somewhat from the general recommendation, but aggressive low-carb dieting during pregnancy carries its own risks.
Why Ketogenic Diets During Pregnancy Raise Red Flags
Given the popularity of keto diets, this comes up constantly. Mouse studies have found that a ketogenic diet during pregnancy alters embryonic organ growth, and those changes may be linked to dysfunction and behavioral changes after birth.11PubMed Central. Effects of a ketogenic diet during pregnancy on embryonic growth in the mouse Animal data does not transfer directly to humans, but the concern aligns with what we know about the fetal brain’s glucose dependency. When maternal carbohydrate intake drops low enough to induce sustained ketosis, the fetus is forced to rely on ketone bodies for fuel to an extent that its developing organs may not be designed to handle. No reputable medical body currently recommends ketogenic diets during pregnancy, and until human trial data says otherwise, the precautionary approach makes sense.
Fat Quality Over Fat Quantity
Total fat intake during pregnancy does not need to change dramatically, but the type of fat you eat has real consequences for fetal development. Docosahexaenoic acid (DHA) and arachidonic acid (AA) are structural building blocks of the central nervous system. The placenta has specific binding and transfer proteins that preferentially shuttle DHA and AA to the fetus, producing higher concentrations of these fatty acids in fetal blood than in maternal blood.12PubMed. Essential fatty acid transfer and fetal development Depleting DHA from the retina and brain has been linked to reduced visual function and learning deficits in animal models, likely because DHA plays critical roles in cell signaling and neurotransmitter function.
This preferential transfer comes at the mother’s expense. Research on phospholipid profiles during pregnancy shows a significant shift of omega-3 and omega-6 fatty acids from the mother to the fetus, and the resulting relative deficiency in maternal circulation suggests dietary supplementation may be warranted.13PubMed. Deficiency of essential fatty acids and membrane fluidity during pregnancy and lactation Practically, this means eating fatty fish a couple of times a week or taking a DHA supplement matters more during pregnancy than at almost any other time of life. Your body will drain its own stores to supply the fetus, and if those stores are thin to begin with, both of you end up short.
Fiber Shapes the Gut in Ways That Matter
Fiber is not a macronutrient in the energy-contributing sense, but it rides alongside carbohydrates in food and has its own pregnancy-specific effects worth knowing about. In the third trimester, people who met the fiber recommendation had greater gut microbial diversity than those who fell short.14PubMed Central. The Relationship Between Fiber Intake and Gut Bacterial Diversity and Composition During the Third Trimester of Pregnancy A more diverse gut microbiome during pregnancy has been associated with better metabolic outcomes and reduced inflammation, though the research is still working out the exact mechanisms in humans.
Animal data adds a practical angle: different types of fiber have different effects. Certain resistant starches boosted short-chain fatty acid production and increased beneficial bacteria while reducing potentially harmful ones.15PubMed Central. Consumption of Dietary Fiber with Different Physicochemical Properties during Late Pregnancy Alters the Gut Microbiota and Relieves Constipation in Sow Model Given that constipation affects a large proportion of pregnancies, getting enough fiber from varied sources (whole grains, legumes, vegetables, fruit) serves double duty: supporting gut health and keeping things moving.
Ultra-Processed Foods and Pregnancy Risk
The macro numbers on a nutrition label can look identical whether the food is a grilled chicken salad or a heavily processed frozen meal, but the outcomes are not the same. A meta-analysis of over half a million participants found that diets high in ultra-processed foods were associated with about a 19 percent higher risk of gestational diabetes and a 28 percent higher risk of preeclampsia.16PubMed Central. The association between ultra-processed food and common pregnancy adverse outcomes: a dose-response systematic review and meta-analysis A dose-response analysis within that same work found that each 100-gram increase in daily ultra-processed food intake was tied to a 27 percent jump in gestational diabetes risk.
Beyond metabolic disease, ultra-processed food intake during pregnancy was linked to about 31 percent higher odds of excessive gestational weight gain, higher levels of the inflammatory marker CRP, and greater postpartum weight retention.17PubMed Central. Associations of ultra-processed food intake with maternal weight change and cardiometabolic health and infant growth The takeaway is not that macros do not matter, but that hitting your protein and carbohydrate targets with minimally processed foods likely produces better outcomes than getting the same numbers from processed alternatives. The food matrix, the micronutrients that come along for the ride, and the absence of industrial additives all seem to play a role.
How Macros Change for Twin Pregnancies
If you’re carrying twins, the standard macro advice needs adjustment. A review of dietary recommendations for twin pregnancy found that the literature specifically emphasizes protein as the macronutrient requiring the most attention: inadequate amino acid supply can harm both fetal and placental development when two babies are drawing from the same maternal pool. The proposed breakdown for twin pregnancies is roughly 20 percent of total energy from protein, 40 percent from carbohydrates, and 40 percent from fat.18PubMed Central. Review of Dietary Recommendations for Twin Pregnancy: Does Nutrition Science Keep Up with the Growing Incidence of Multiple Gestations? That fat proportion is higher than what most singleton pregnancy guidelines suggest, reflecting the greater caloric demand and the fact that fat is the most calorie-dense macronutrient.
For context, a singleton pregnancy might aim for 15 to 20 percent protein, 45 to 65 percent carbs, and 20 to 35 percent fat. The twin recommendation compresses the carbohydrate share and expands fat, while keeping protein at the upper end. Calorie needs are also substantially higher: most estimates add 500 to 600 extra calories per day for twins compared to a singleton pregnancy, starting earlier and staying higher through delivery.
Pregnancy After Bariatric Surgery
A growing number of pregnancies occur after weight-loss surgery, and the macro challenges are unique. The combination of a surgically reduced stomach capacity, frequent nausea and vomiting, and the increased nutritional demands of pregnancy creates a real risk of protein and calorie malnutrition.19PubMed Central. Pregnancy after Bariatric Surgery: Nutrition Recommendations and Glucose Homeostasis Micronutrient deficiencies are also common because the surgically altered digestive tract absorbs certain vitamins and minerals less efficiently.
For people in this situation, hitting pregnancy protein targets is especially difficult because the volume of food they can eat at one sitting is small. Spreading protein intake across five or six small meals per day, prioritizing high-protein foods at every eating occasion, and working with a dietitian who understands both bariatric physiology and prenatal nutrition is generally the recommended approach. Relying on protein supplements (shakes, collagen peptides, protein bars) is more common in this population than in the general pregnant population, and it is one of the few contexts where that reliance is broadly supported by clinical guidance.
Meal Timing and Circadian Patterns
The emerging science of when you eat, not just what you eat, has started to touch pregnancy research. Maternal circadian eating patterns and meal frequency have been linked to changes in glucose metabolism during pregnancy.20PubMed. Time-restricted feeding during embryonic development leads to metabolic dysfunction in adult rat offspring Animal research found that restricting feeding to narrow time windows during embryonic development led to metabolic problems in offspring as adults. This does not mean intermittent fasting during pregnancy is proven harmful in humans, but it adds to the biological plausibility that skipping meals or compressing all eating into a short window could have downstream effects on fetal metabolic programming.
In practice, most prenatal nutrition guidance already emphasizes eating regularly throughout the day, partly to manage nausea and blood sugar swings and partly to maintain a steady supply of glucose to the placenta and fetus. The circadian research gives a mechanistic reason behind that advice: your body’s glucose handling changes across the day, and so does the placenta’s uptake of nutrients. Eating at roughly consistent times, rather than front-loading or back-loading calories, likely gives the fetal environment the most stable fuel supply.
The DHA Supply Chain From Mother to Fetus
The omega-3 story deserves a closer look because it intersects with the broader question of fat macros in a way many tracking apps miss. When you log “fat grams” in a macro tracker, the number treats olive oil, butter, and salmon as interchangeable. They are not. The placenta actively concentrates DHA and arachidonic acid and deliberately excludes shorter-chain fats like linoleic acid.21PubMed. Essential fatty acid transfer and fetal development The transfer system is designed to funnel the building blocks of neural tissue toward the fetus, even at the cost of depleting maternal reserves.
This selective transfer explains why maternal DHA status tends to decline across pregnancy if dietary intake does not compensate. It also explains the emphasis on seafood or supplemental DHA rather than just “eating enough fat.” Two to three servings of low-mercury fish per week, or 200 to 300 milligrams of supplemental DHA daily, is the range most professional bodies suggest. If your total fat macros look fine but none of it comes from marine sources, you could still be undersupplying the nutrient your baby’s brain needs most.
What Macro Trackers Get Wrong About Pregnancy
Most macro-tracking apps default to non-pregnant adult settings, and the gap between those defaults and pregnancy-appropriate targets is bigger than many users realize. A standard “balanced” macro split might put protein at 0.8 grams per kilogram, carbs at 45 to 55 percent of energy, and fat at 25 to 35 percent. During pregnancy, protein needs may be 50 to 90 percent higher than that baseline, depending on the trimester and your body weight. Carbohydrate intake should stay above 175 grams per day at minimum, and likely above 220 grams if newer placental glucose estimates hold up. Fat quality shifts from a nice-to-have concern to a developmental priority.
Another common tracking mistake is fixating on daily macro ratios without considering total calories. Hitting a 30-percent protein target means very different absolute grams at 1,800 calories versus 2,400 calories, and the fetus cares about absolute grams, not percentages. If nausea or food aversion cuts your total intake, your percentage-based targets may look fine while your absolute protein and carbohydrate intake are both short. In early pregnancy especially, when appetite is unreliable, tracking absolute grams alongside ratios gives a clearer picture.
There is also the issue of food quality lurking beneath the macro numbers. Two diets with identical macro splits can produce different pregnancy outcomes depending on how processed the food is, as the ultra-processed food data suggest. A macro tracker treats a protein bar and a piece of grilled fish as equivalent when they hit the same protein number. Your body, your gut microbiome, and your developing baby do not experience them equivalently. Macros are a useful framework, but they are the scaffolding, not the whole building.