The process of pregnancy is lengthy and divided into various stages, with different nutritional needs for fetal growth in each period. Many parents begin planning for their child’s health from the moment they learn about the pregnancy, ensuring that they don’t fall behind right from the start. For instance, many expectant mothers opt to supplement with DHA fish oil and prenatal multivitamins. This article focuses on analyzing and organizing the nutrients that should be supplemented during each stage of pregnancy.
Why is it often heard that pregnant women should supplement with DHA fish oil?
The entire duration of pregnancy is about 280 days (40 weeks), with less than 37 weeks being considered premature and over 42 weeks being considered post-term. Additionally, fetal development can be divided into three main stages:
- Embryonic Stage (0-2 weeks): This is the process of successful implantation of the fertilized egg.
- Embryonic Period (2-8 weeks): During this stage, the embryo undergoes differentiation into three primary germ layers – the ectoderm, mesoderm, and endoderm. From these layers, various tissues and organs will develop.
- Fetal Stage (9-40 weeks): The fetus undergoes rapid growth, increasing from around 6 grams to a final weight of 3000-3500 grams.
If we take a closer look at the process of embryonic development, what are the important milestones? Around 3 weeks after fertilization, the neural tube begins to form. The 4th week sees the development of the head and trunk. By the 8th week, the human form is recognizable, and the heart begins to beat. Gender can be confirmed by the 12th week. Around 20 weeks, rapid bone growth occurs, and fetal movement can be observed. By 24 weeks, the retina and brain nerve fibers start functioning. Around 28 weeks, lung alveoli gradually mature. Starting around the 36th week, the body begins to store nutrients (such as glycogen, iron, and calcium), most of the organs have completed differentiation and have basic functionality.
Experts encourage pregnant women to supplement with DHA for several reasons. Aside from being a vital component of brain and retinal cell membranes [1], Omega-3 fatty acid supplementation helps reduce the risk of low birth weight and premature birth [2][3]. It also contributes to the fetal immune system, reducing the risks of conditions such as eczema, food allergies [4], and even lower respiratory tract infections [5]. Supplementing with DHA during pregnancy not only benefits the fetus but also reduces the risk of postpartum depression in the mother[6][7], making it a concept of “eating for two.”
How much DHA should pregnant women consume in a day?
Although the body has the potential to convert and synthesize DHA, the efficiency of this conversion process is extremely low. Therefore, the primary source of DHA is obtained through dietary intake.
- The Ministry of Health and Welfare recommends that the reference intake of Omega-3 fatty acids for pregnant women remains the same as during non-pregnancy periods (constituting 0.6-1.2% of total caloric intake).
- The National Institutes of Health (NIH) in the United States suggest an additional intake of 300 milligrams of Omega-3 fatty acids during pregnancy [8].
- The Food and Agriculture Organization (FAO) of the United Nations advocated in 2010 that pregnant women should supplement with at least 200 milligrams of DHA daily [9].
What nutrients should be supplemented during pregnancy?
The types of nutrients needed by the fetus are quite similar to those required by adults, but there are significant differences in terms of the amounts needed. Therefore, what nutrients the mother supplements will directly affect the nutrients the fetus receives. The Eighth Edition of Taiwan’s Dietary Reference Intakes (DRIs) for the Taiwanese Population provides enhanced nutrient recommendations for each stage of pregnancy, along with upper limits for intake. This can be divided into three main categories:
1. Energy, the Three Major Nutrients, and Fat-Soluble Vitamins
| Energy (kcal) | Carbohydrates (g) | Protein (g) | Dietary Fiber (g) | Vitamin A (μg RE) | Vitamin D (μg) | Vitamin E (mg α-TE) | Vitamin K (μg) | |
| 19-50 years old female | 1450-2100 | 100-135 | 50 | 20-29 | 500 | 10 | 12 | 90 |
| first trimester | 1450-2100 | 100-135 | 60 | 20-29 | 500 | 10 | 14 | 90 |
| second trimester | 1750-2400 | 135-175 | 60 | 25-34 | 500 | 10 | 14 | 90 |
| third trimester | 1750-2400 | 135-175 | 60 | 25-34 | 600 | 10 | 14 | 90 |
| maximum | none | none | none | none | 3000 | 50 | 1000 | none |
2. Water-Soluble Vitamins
| Vitamin C (mg) | Vitamin B1 (mg) | Vitamin B2 (mg) | Niacin (mg NE) | Vitamin B6 (mg) | Vitamin B12 (mg) | Folate (μg) | Folic Acid (mg) | Biotin (μg) | Pantothenic Acid (mg) | |
| 19-50 years old female | 100 | 0.9 | 1 | 14 | 1.5 | 2.4 | 400 | 390 | 30 | 5 |
| first trimester | 110 | 0.9 | 1 | 14 | 1.9 | 2.6 | 600 | 410 | 30 | 6 |
| second trimester | 110 | 1.1 | 1.2 | 16 | 1.9 | 2.6 | 600 | 410 | 30 | 6 |
| third trimester | 110 | 1.1 | 1.2 | 16 | 1.9 | 2.6 | 600 | 410 | 30 | 6 |
| maximum | 2000 | none | none | 35 | 80 | none | 1000 | 3500 | none | none |
3. Macro Minerals
| Calcium (mg) | Phosphorus (mg) | Magnesium (mg) | Iron (mg) | Zinc (mg) | Iodine (μg) | Selenium (μg) | Fluoride (mg) | |
| 19-50 years old female | 1000 | 800 | 320 | 15 | 12 | 150 | 55 | 3 |
| first trimester | 1000 | 800 | 355 | 15 | 15 | 225 | 60 | 3 |
| second trimester | 1000 | 800 | 355 | 15 | 15 | 225 | 60 | 3 |
| third trimester | 1000 | 800 | 355 | 45 | 15 | 225 | 60 | 3 |
| maximum | 2500 | 4000 | 700 | 40※ | 35 | 1000 | 400 | 10 |
※ The upper limit of 40 milligrams for iron refers specifically to the upper limit for iron supplements.
You can start by assessing your daily dietary habits to identify any deficiencies in nutrients, or you can directly supplement with a comprehensive vitamin. The following is a compilation of nutrients that need special attention during different stages of pregnancy, based on daily recommended intake, typical dietary habits of the population, and biochemical values of nutrient levels in the blood.
the first trimester of pregnancy (0-12 weeks)
During the first trimester of pregnancy (0-12 weeks), it’s important to start supplementing with the following nutrients:
Folate (Folic Acid)
Insufficient folate intake can lead to anemia and increase the risk of neural tube defects in the fetus. Adequate folate supplementation helps prevent these conditions.
Vitamin B12
Vitamin B12 is crucial for functions such as blood formation, cell division, and nervous system maintenance. Deficiency can result in megaloblastic anemia and damage to the nervous system. Vegetarians and vegans are at a higher risk of B12 deficiency due to its primary animal-derived sources.
Choline
Choline, a vitamin-like nutrient, is essential for the composition of cell membrane phospholipids and the synthesis of the neurotransmitter acetylcholine (Ach). Its deficiency during pregnancy can lead to neural tube defects in the fetus.
Iodine
Increased basal metabolic rate and thyroid hormone secretion occur during pregnancy, leading to a higher demand for iodine. Iodine deficiency can result in cretinism, a condition affecting brain development and causing growth retardation and even stillbirth in the fetus.
the second trimester of pregnancy (16-24 weeks)
During the second trimester of pregnancy (16-24 weeks), it’s important to start supplementing with the following nutrients:
Omega-3 Fatty Acids (DHA > EPA)
By the 24th week of embryonic development, the retinal and brain nerve fibers become active. To ensure the necessary Omega-3 nutrients are available for their proper functioning, supplementation should begin before this milestone.
Calcium + Vitamin D
Around the 20th week, the fetus experiences rapid bone growth, necessitating an increased supply of calcium. Additionally, as blood volume increases during pregnancy, blood pressure can rise, making calcium vital for maintaining stable blood pressure. It’s recommended to supplement calcium with vitamin D, as it enhances calcium absorption.
Fiber + Probiotics
As the fetus grows and exerts pressure on the gastrointestinal tract, constipation can occur in pregnant women. Supplementation with probiotics and fiber, combined with adequate hydration, regular exercise, and proper sleep, can alleviate constipation symptoms.
the third trimester of pregnancy (28 weeks to birth)
During the third trimester of pregnancy (28 weeks to birth), it’s important to start supplementing with the following nutrient:
Iron
As the fetus continues to grow and develop, along with the increase in blood volume, the demand for hemoglobin naturally rises. Furthermore, in the later stages of pregnancy, the fetus begins to store nutrients in preparation for birth. Additionally, there might be instances of bleeding during childbirth. Therefore, adequate iron supplementation during the later stages of pregnancy is essential.
What are the precautions for supplementing nutrients during pregnancy?
Throughout each stage of pregnancy, it’s important to consider various aspects of nutrient supplementation, and of course, be aware of the precautions when supplementing nutrients.
- Avoid alcohol intake during pregnancy.
- Tea, coffee, or any foods containing caffeine should also be avoided, especially in the first trimester. If consumption is necessary, limit daily caffeine intake to 200 milligrams or less.
- When supplementing vitamins and minerals, focus on meeting the recommended daily intake and avoid exceeding the upper limits, particularly for certain fat-soluble vitamins like A and D.
- For pregnant women supplementing with DHA through deep-sea fish consumption, be cautious of ocean pollution issues. Alternatively, choose fish oil DHA products that are tested for plasticizers and heavy metals.
How nutrients should be supplemented during pregnancy depends on individual circumstances and dietary habits. Factors such as lifestyle and personal health conditions need to be considered. It’s not necessarily better to take more supplements. By adhering to the basic principles mentioned above, you can ensure the health and well-being of both mother and baby during pregnancy.
