Vitamin A and omega-3 fatty acid deficiency increase the risk of preterm birth

If a woman gives birth before 37 weeks of pregnancy, the baby is considered premature. The earlier the baby is born, the greater the risk of complications, death, or serious long-term consequences. As is well known, diet during pregnancy is highly important, and it now appears that a deficiency of vitamin A and omega-3 fatty acids such as EPA and DHA increases the risk of preterm birth. This is demonstrated by a large Chinese study in which the researchers also describe the role these nutrients play during pregnancy. Pregnant women should therefore pay attention to getting enough vitamin A and omega-3 fatty acids while at the same time avoiding excessive intake of vitamin A and/or omega-6 fatty acids.

A normal pregnancy lasts 40 weeks and is divided into three periods known as trimesters. If a baby is born before 37 weeks, the risk of immature organs, breathing difficulties, infections, and developmental disorders increases. The risk increases the earlier the baby is born. Although modern medicine can help many premature babies, it cannot help all of them, and preterm birth remains the leading cause of death worldwide among children under five. There is therefore every reason to support a normal pregnancy and maintain good dietary habits. In addition, pregnant women are advised to take folic acid and vitamin D supplements, particularly to prevent neural tube defects and osteoporosis. However, relatively little has been known about pregnant women's intake of vitamin A and polyunsaturated fatty acids such as omega-3 and omega-6 and how it affects the risk of preterm birth. The new study therefore aimed to investigate this in greater detail.
The study included 8,897 pregnant Chinese women, of whom 880 gave birth prematurely, while the remaining 8,017 served as the control group. All participants were registered at the Chinese hospital Perinatal Medicine Center and Gansu Provincial Maternity and Child-Care Hospital between March 2018 and March 2019.
The participants' nutrient intake was assessed through a statistical analysis of questionnaires stored in a database. This information was then compared with whether the pregnant women gave birth at term or before 37 weeks, when the baby is considered premature.

The study revealed the following:

• An insufficient intake of vitamin A and polyunsaturated fatty acids such as omega-3 and omega-6 during the third trimester increased the risk of preterm birth
• There was a U-shaped association during the third trimester, which particularly means that excessive intake of vitamin A and polyunsaturated fatty acids such as omega-6 also increased the risk of preterm birth

The researchers therefore conclude that preterm birth may be associated with deficiencies in vitamin A and polyunsaturated fatty acids, both before conception and during pregnancy. On the other hand, pregnant women should not consume excessive amounts of these nutrients either. The researchers therefore recommend that pregnant women obtain sufficient amounts of vitamin A and polyunsaturated fatty acids both before and during pregnancy.

The importance of vitamin A during pregnancy

Vitamin A is a fat-soluble vitamin that plays an important role in placental function, fetal development, and immune function. Epidemiological studies indicate that vitamin A deficiency is significantly associated with complications during pregnancy.
Preformed vitamin A (retinol) is found in animal sources such as liver, liver pâté, fatty fish, eggs, butter, and cheese. The precursor beta-carotene is found in plant sources such as carrots, spinach, tomatoes, and bell peppers.
The recommended daily intake is 800 micrograms, which can easily be obtained from a varied and healthy diet. Nonetheless, vitamin A deficiency is one of the most widespread nutrient deficiencies worldwide.
Pregnant and breastfeeding women should not consume more than 1,000 micrograms of vitamin A per day, as this can harm the fetus and breast milk. Pregnant women should therefore avoid eating liver, which contains particularly high amounts of vitamin A, or taking vitamin supplements unless they are specifically formulated for pregnant women.

The importance of omega-3 and omega-6 fatty acids during pregnancy

Omega-3 and omega-6 fatty acids are found in cell membranes, where they regulate inflammation and a wide range of metabolic processes that are also important for pregnancy and fetal development. It is important that the two fatty acids are consumed in the right balance so that the many metabolic processes can proceed normally.
Fatty fish contains the omega-3 fatty acids EPA and DHA, which are particularly important for the development of the fetal brain and nervous system. It has also been shown that pregnant women with low levels of these omega-3 fatty acids have a significantly greater risk of giving birth prematurely compared with pregnant women who have higher levels of these omega-3 fatty acids. This is shown by a previous Danish-American study published in the Harvard Gazette.
It is also a problem that many pregnant women are afraid to eat fatty fish because of concerns about its mercury content, which is highest in larger predatory fish such as tuna. Pregnant women should therefore aim to eat fatty fish such as anchovies, herring, mackerel, and wild salmon, which are lower down the food chain, or take a high-quality fish oil supplement.
Good sources of omega-6 fatty acids include nuts, kernels, seeds, and animal products such as eggs and meat. However, the modern diet often contains far too many omega-6 fatty acids from various vegetable oils (e.g., safflower, sunflower, corn, and grapeseed oils), as well as margarine, dressings, fried foods, chips, French fries, mayonnaise, deli salads, ready-made meals, and other processed foods. This often creates an imbalance with omega-3 fatty acids, which can negatively affect overall health. As mentioned above, this imbalance also increases the risk of preterm birth and other complications during pregnancy.

References

Lei Cao et al. Maternal dietary vitamin A and polyunsaturated fatty acids intake and risk of preterm birth; a nested case-control study. PeerJ 2026

Chris Sweeney. Pregnant women encouraged to eat cold-water fish. The Havard Gazette 2018