Introduction
Fish oil during pregnancy has become a common recommendation in modern maternal nutrition. Fish oil is a natural oil produced from fatty fish such as salmon, sardines, anchovies, and mackerel. It contains two important omega-3 fatty acids: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). These nutrients are essential for fetal growth, especially for the development of the brain, eyes, nervous system, and immune system. They also support the mother’s heart, blood circulation, and recovery after childbirth.
A pregnant woman can obtain omega-3 fatty acids from eating fish, taking fish oil supplements, or using algae-based DHA if she does not consume animal products. Because many women do not eat fish regularly, supplements are often used to ensure the right daily intake. Research over the past decades shows that fish oil during pregnancy is safe when taken in recommended doses and can benefit both the mother and the baby.
Table of Contents
Why Omega-3 Fatty Acids Are Important During Pregnancy
During pregnancy, the baby’s body grows rapidly, and the brain grows faster than any other organ. DHA is one of the main structural components of brain cells. When the mother takes fish oil during pregnancy, DHA enters the placenta, then the baby’s bloodstream, and becomes part of the developing brain and eyes.
The retina of the eye also contains large amounts of DHA. This nutrient helps form clear vision, good contrast sensitivity, and proper communication between eye tissue and the brain. EPA, the second omega-3 acid in fish oil, supports blood flow and reduces inflammation, helping the placenta deliver oxygen and nutrients to the fetus.
Because the baby needs DHA, the mother’s body transfers DHA from her own stores. If the mother does not consume enough omega-3, her body may become depleted, which can affect her skin, mood, energy, and hormone balance. Fish oil during pregnancy prevents this depletion by supplying both mother and baby with the necessary amount of DHA and EPA.
Benefits for the Baby
Brain and cognitive development
One of the strongest reasons doctors recommend fish oil during pregnancy is to support the baby’s brain. Many scientific studies show that babies whose mothers take DHA have better brain and nervous system development. These babies may show better attention, stronger problem-solving, faster learning, and better coordination as they grow. While development depends on many factors like genetics and environment, DHA is a required nutrient for healthy brain formation.
Eye and vision development
The retina of the eye needs DHA for sharp vision. Babies whose mothers take fish oil during pregnancy often show better visual development in infancy. Because the eyes develop rapidly in late pregnancy and early life, DHA remains important during breastfeeding as well.
Healthy birth weight and growth
Research suggests that fish oil during pregnancy can support a healthier birth weight. Babies may have stronger bones, better muscle tone, and healthier fat distribution. Fish oil does not lead to childhood obesity. Instead, it helps normal growth and may support bone and immune development.
Lower risk of preterm birth
Preterm birth, before 37 weeks, is one of the most serious pregnancy complications worldwide. Babies born too early may face breathing problems, infections, feeding difficulties, and longer hospital stays. Multiple studies have shown that fish oil during pregnancy can slightly reduce the risk of preterm labor. DHA appears to help stabilize uterine muscles and reduce inflammatory triggers that can cause early labor.
Benefits for the Mother
Cardiovascular support
A pregnant woman’s bloodstream increases by almost 50 percent, and her heart works harder than usual. EPA supports healthy circulation and lowers inflammation, helping the cardiovascular system manage pregnancy stress. Fish oil during pregnancy may support healthy blood pressure and vessel function.
Possible reduction of preeclampsia risk
Preeclampsia is a dangerous pregnancy condition involving high blood pressure and organ stress. Some studies suggest fish oil during pregnancy may lower risk by improving blood flow and reducing inflammation. The results are not the same in every study, so fish oil is not a treatment, but it may contribute to a healthier pregnancy.
Mental health and postpartum mood
Many mothers experience emotional changes after birth. DHA is involved in brain chemistry and hormone regulation. Women with low omega-3 levels are more likely to experience mood problems. Populations where seafood intake is high report fewer cases of postpartum depression. Taking fish oil during pregnancy may support emotional well-being, although it should not replace medical or psychological care.
Recovery after childbirth
After birth, the body repairs tissue, rebalances hormones, and recovers from inflammation. Omega-3 fatty acids help with immune function and cell repair. Women who use fish oil during pregnancy maintain better body stores of DHA, which may support recovery in the postpartum period.
Recommended Intake and Sources
Most medical organizations recommend 200–300 mg of DHA per day during pregnancy and breastfeeding. Some supplements also contain EPA, which is useful for inflammation control and circulation. Higher doses may be used in clinical studies, but very high doses should only be taken under medical supervision.
Dietary sources
Safe, low-mercury fish include:
- salmon
- sardines
- trout
- anchovies
- light tuna
- cod
Eating fish two or three times per week provides DHA, EPA, vitamin D, iodine, calcium, and high-quality protein. Women who eat enough fish may not need supplements every day. However, many women do not eat fish regularly due to taste, cost, or digestive discomfort, so supplements are a common choice.
Fish oil supplements
Fish oil supplements are available as capsules or liquid. Capsules are easy to swallow and are better for people who dislike the taste of fish. Enteric-coated capsules can help prevent fishy burps. Women who follow vegetarian or vegan diets can use algae-based DHA supplements, which provide the same benefits without fish.
Safety and Mercury Concerns
One of the most common fears about eating fish during pregnancy is mercury exposure. Mercury can affect brain development, especially when found in large predatory fish. To stay safe, pregnant women should avoid:
- shark
- swordfish
- king mackerel
- tilefish
These fish contain the highest mercury levels. Low-mercury fish are considered safe. Fish oil supplements are usually purified, and high-quality brands remove contaminants. Most scientific reviews show that purified fish oil during pregnancy contains very little mercury and is safe for both mother and baby.
Side effects
The most common side effects of fish oil during pregnancy are mild:
- soft stools
- fishy taste
- slight stomach discomfort
These effects are usually reduced when the supplement is taken with meals. There is no evidence that normal supplement doses increase bleeding risk or miscarriage risk. Fish oil body oils, not fish liver oils, are recommended. Liver oils contain excess vitamin A, which can be harmful in pregnancy and should be avoided.
What Research Shows
Scientists have studied fish oil during pregnancy for many years. Some results are strong and consistent, while others vary. The most consistent findings include:
- support for fetal brain development
- improved visual development
- slightly longer pregnancy duration
- lower risk of early preterm birth
- healthy birth weight
Other possible benefits include lower postpartum depression and reduced inflammation, but results are mixed and still being researched. Even with mixed findings, the biological logic is clear: DHA is a required nutrient for the baby’s brain and eyes. If mothers do not eat fish regularly, fish oil during pregnancy is a practical way to provide it.
Practical Guidelines for Pregnant Women
- Eat low-mercury fish two or three times per week if possible
- If you do not eat fish, take a DHA supplement daily
- Choose purified, tested brands
- Avoid cod liver oil and other fish liver oils
- Vegetarian women can use algae DHA oil
- Speak to a healthcare provider before taking very high doses
Fish oil during pregnancy works best when taken consistently. Small daily amounts are more effective than occasional large doses.
Who Should Consider Supplementation
Some women may benefit even more from fish oil during pregnancy, including those who:
- rarely eat seafood
- are vegetarian or vegan
- have high-risk pregnancies
- are carrying twins or multiples
- have a history of inflammation or depression
For these women, supplements provide a steady and reliable source of DHA.
Frequently Asked Questions
Is fish oil during pregnancy safe?
Yes. Purified fish oil is considered safe by nutrition experts and obstetricians.
Can it be taken with prenatal vitamins?
Yes. Most prenatal vitamins have little or no DHA, so combining both is common.
When should supplementation start?
It can begin before pregnancy or at any time during pregnancy. Many women continue while breastfeeding.
Can I get enough from food alone?
Yes, if you eat low-mercury fish several times a week. If not, supplements help meet the recommended intake.
Conclusion
Fish oil during pregnancy provides DHA and EPA, two essential nutrients for fetal growth and maternal health. DHA supports the baby’s brain and eye development, while EPA helps circulation and reduces inflammation. Studies show that using fish oil during pregnancy can reduce the risk of preterm birth, improve birth weight, and support healthy nervous system development. The supplement has a strong safety record when used in recommended doses and when purified brands are chosen.
Most medical groups suggest about 200–300 mg of DHA per day for pregnant and breastfeeding women. Omega-3 can come from low-mercury fish, purified fish oil supplements, or algae-based DHA for vegetarians. Fish oil during pregnancy is not a treatment for disease, but it is a simple, safe, and scientifically supported way to promote a healthy pregnancy and a healthy baby.
