Pregnancy and breastfeeding are very important periods in a woman’s life. Healthy eating during pregnancy is more important than ever. Every woman has a different body and different nutritional needs, but during pregnancy and lactation every woman must consume a diet that includes a variety of foods, in small and regular meals, to provide all the nutrients she needs. The diet of pregnant women must also provide them with the nutrients necessary for the proper development of the fetus.

Omega-3 are essential fatty acids that should be consumed in our diet. The human body can synthesize many other fatty acids, such as saturated and monounsatu­rated fatty acids, but it cannot synthesize fatty acids with the first double bond to omega-3 and omega-6. Essential fatty acids, omega-3 and omega-6, are lipids that cannot be synthesized in the body and must be ingested through diet or dietary supplements⁽¹⁾.

The current recommendations for the daily diet of pregnant women and during breastfeeding are: 2-3 servings of legumes, 1-2 servings of fish, 1-2 servings of chicken/turkey, one serving of red meat. The pregnant woman is recommended to consume at least 120 to 340 g of fish per week if at least one serving is fatty fish (herring, mackerel, sardines, salmon, catfish etc.), which are good sources of omega-3 essential fatty acids⁽²⁾.

Polyunsaturated fatty acids act as precursor molecules for eicosanoids. They regulate fundamental physiological processes (division and growth cell, hormonal secretions and cell membrane transport activity)⁽³⁾.

Omega-3 polyunsaturated fatty acids belong to the family of polyunsaturated fatty acids (PUFA) with a long chain of carbon atoms and are represented by alpha-linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Alpha linoleic acid is considered essential because it cannot be synthesized by the body, the main source of food being food. ALA can be transformed in human tissues to EPA and DHA, but the amounts are not significant (less than 5%)⁽²⁾.

Alpha-linolenic acid (ALA) is found in vegetable fats – in high concentrations in flax seeds, rape, nuts and soybeans. In general, plants contain ALA and not EPA or DHA. Eicosapentaenoic acid and docosahexaenoic acid are found in fish fat. Most experts recommend eating fish and seafood as a source of omega-3 in the context of a healthy diet, along with regular physical activity^(1,4).

Depending on the fat content, we distinguish between species of lean fish (cod, pikeperch, perch and hake) and fatty fish (herring, mackerel, sardines, salmon and cat­fish). EPA is found in abundance in fatty fish (tuna, salmon, herring and cod liver) and in marine animal oil. All forms of fish and seafood contain omega-3. Fatty fish contains a higher amount of omega-3 compared to lean fish⁽⁴⁾.

The increased intake of EPA and DHA in the body is considered to be improved by the constant consumption of oil from cold-water fish and krill. Crude fish oil contains 18% EPA and 12% DHA; by special processing, it can be concentrated, obtaining oil with 33% EPA and 22% DHA. Another essential source of omega-3 fatty acids is currently seaweed (Crypthecodinium cohnii and Schizochytrium microalgae)⁽⁵⁾.

Materials and method

The aim of our research is to highlight the recommendation of consumption of essential polyunsaturated fatty acids omega-3 during pregnancy and lactation and to present the results of the monitoring of children whose mothers received or not optimal amounts of omega-3 during pregnancy, at different intervals until the age of 8 years old.

In order to achieve our objectives, we looked for clinical trials collected from three databases: Cochrane Pregnancy and Childbirth’s Trials Register, ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) (August 16, 2020) and from prospective longitudinal studies. Using the keywords “omega-3” OR “polyunsaturated fatty acids” AND “pregnancy” OR “gestation”, we selected randomized controlled trials (RCTs) which compared the group that included women who were given omega-3 fatty acids during pregnancy (in the form of supplements or foods, either on their own or with a co-intervention) with the group who received placebo or lacked omega-3 administration. Children were evaluated after birth at different time intervals, and the results of different groups were compared.

Results and discussion

We found a number of 107 studies conducted between 2007 and 2020 that met the established search criteria, with over 2400 articles that published the results of these studies. The number of randomized controlled trials in the three databases is specified in Table 1.

What are the recommended doses
of omega-3 polyunsaturated fatty acids
in pregnancy and lactation?

For optimizing results during pregnancy and for the health of the fetus, the guidelines recommend that the pregnant woman consume at least 200 mg of DHA per day. A pregnant woman can achieve this threshold by consuming one to two servings of seafood per week⁽⁶⁾.

Fruits may also contain organic mercury and other harmful toxins (e.g., polychlorinated biphenyls; PCBs), which could be harmful to the fetus during growth. For this reason, the FDA/EPA recommends limiting the consumption of fish to two servings (approximately 340 g of seafood) per week^(6-9).

According to the European Food Safety Authority (2012), an amount of 250 mg of omega-3 per day is sufficient as consumption, before and during pregnancy, for the beneficial effects on the pregnant woman and the fetus⁽¹⁰⁾.

Recent studies have shown that, despite the FDA/EPA opinion, which recommends up to 2 servings of fish as safe in pregnancy, many pregnant women consume little or no fish during this period, thus depriving the fetus of the necessary nutrients. Pregnant women indicated that the advice of a doctor played a key role in their decision to eat fish during pregnancy⁽¹¹⁾.

What are the effects of consuming omega-3 polyunsaturated fatty acids on the fetus and mother during pregnancy?

Numerous benefits have been associated with the consumption of omega-3 polyunsaturated fatty acids during pregnancy or after birth when fish or seafood are found in the diet. Polyunsaturated fatty acids (PUFAs) are necessary for the body’s physiological functions, including oxygen transport, energy storage, cell membrane function, regulation of inflammation and cell proliferation, but also for the growth and the development of many systems and organs during pregnancy, the most important being the brain and the eye^(7,8,12-14).

The preponderance of the data suggests that the intake of omega-3 polyunsaturated fatty acids during pregnancy is important for the development of the fetal brain and for the subsequent neurodevelopment of the baby. Fetal brain growth accelerates in the second half of pregnancy, and the growth rate remains high in the infant in the first year and continues to grow for the next few years. Dietary deprivation of omega-3 polyunsaturated fatty acids in pregnancy is associated with impaired development and behaviour^(12-15).

In a longitudinal prospective study – Avon Longitudinal Study of Parents and Children (ALSPAC) – that recruited 13,761 pregnant women, they were asked to complete opinion polls on seafood consumption during pregnancy and to answer questions about their children’s development and behavior. A number of 10,000 children were evaluated at six months, one year and a half (18 months), two years and a half (30 months), three years and a half (42 months) and six years and a half (81 months) and at eight years. The respondents were grouped according to their seafood consumption into several study groups: no seafood consumption, 1 to 340 g per week, and more than 340 g per week consumption⁽¹⁶⁾.

Mothers who ate more than 340 g of seafood per week had children who did not show poorer results in verbal and IQ performance tests than children born of mothers who ate less than 340 g per week of seafood. Children born to mothers who did not report any seafood intake during pregnancy had the highest risk of side effects or suboptimal test results, with the lowest quartile for verbal test and IQ performance at 8 years of age, behavioral problems at 7 years of age and poor early development scores on tests to assess fine motor skills, social behaviors, skills and communication skills. For those women who ate seafood during pregnancy and in whom seafood consumption was higher, it was found that the likelihood of having the baby results below the optimal level was reduced^(16-19).

Increasing the intake of omega-3 during pregnancy, either through supplements or in food, may reduce the incidence of premature birth (before 37 weeks and before 34 weeks; Figure 1) and may lead to a less likelihood of having a child small at birth. Women who take omega-3 supplements during pregnancy may also be more likely to have longer pregnancies^(20,21).

The rates of low birth weight (below 2500 g) showed a 10% relative risk reduction with omega‐3 LCPUFA compared with no omega‐3 (RR 0.90; 95% CI; 0.82 to 0.99; 15 trials, 8449 participants) – Figure 2. No obvious asymmetry was observed on visual assessment of a funnel plot for this outcome^(20,21). 

The meta-analysis included 40 randomized controlled trials (RCTs; this type of study provides the most reliable results, and involved 19,927 women), conducted mostly in middle- or high-income countries, and evaluated both high-risk women, the risk of preterm birth, as well as women without this risk. One group of pregnant women received omega-3 LCPUFA (long-chain polyunsaturated fatty acids) and, in studies, they were compared with another group of women who received placebo (they thought they were receiving omega-3 LCPUFA, but it was a placebo) or with another group of women who did not receive omega-3 LCPUFA at all^(12,13).

The quality of evidence in the included studies ranged from high to very low; this determined the certainty of the findings for different results. The incidence of premature birth (before 37 weeks) and very premature birth (before 34 weeks) was found to decrease in women who received omega-3 LCPUFA compared to women who did not receive additional omega-3. There were also fewer low-birth-weight babies. However, omega-3 LCPUFA probably increased the incidence of pregnancies that continued over 42 weeks^(17-19).

Recent studies have shown that the intake of omega-3 fatty acids seems to be important during breastfeeding. Women who were breastfeeding and who received 200 mg of DHA per day in their diet for four months had infants who had sig­ni­fi­cantly better results on the Bayley Psychomotor Develop­ment Index tests performed after 30 months, compared with wo­men who received a vegetable oil supplement^(12,15).

Fish oil supplements are given during pregnancy, and lactation also leads to a lower risk of allergies in infants⁽²²⁾. During the first 12 months of monitoring, children born from mothers who received omega-3 had a decreased risk of developing food allergies and IgE-associated eczema.

The implications of omega-3 on mothers’ health showed that a sufficient intake during pregnancy decreases the risk of preeclampsia and combats postnatal depression among mothers^(23,24). Other symptoms of omega-3 fatty acid deficiency in the mother include extreme fatigue, memory impairment, dry skin, changes in mood to depression and cardiovascular disorders^(25,26).

Conclusions

The results of the clinical studies confirm the association of an optimal intake of EPA/DHA with the favorable evolution of pregnancy. An enriching diet with omega-3, before and during pregnancy, can have beneficial effects for both mother and fetus. According to EFSA (2012), an amount of 120 to 340 mg of omega-3 per day (medium: 250 mg of omega-3 per day) is sufficient before and during pregnancy for the beneficial effects of the cardiovascular, ocular and central nervous system.

Omega-3 fatty acids ensure the development of the brain, the nervous system and the formation of the fetal retina and contribute to the normal psychomotor development of the fetus and to the normal growth in the uterine cavity. Concurrently, a sufficient intake of omega-3 fatty acids during pregnancy decreases the risk of preeclampsia, combats postnatal depression and reduces the risk of premature birth. 

Conflicts of interests: The authors declare no conflict of interests.