Role of Nutrition in the First Trimester of Pregnancy

When it comes to pregnancy, every household has different traditions that they follow or advice to make sure that the mother and child are both happy and healthy. Everyone wants the best for them, but sometimes all these advices can get a little overwhelming for the mother. She may be confused what to do and when to do them. She has to make changes in her lifestyle all while major changes are happening in her body as well.

What are these changes that occur in a pregnant mother?

Well, they are known as physiological changes which means changes that happen in her organ systems. Let’s find out what they are!

There are many organ systems in our body dies like cardiovascular, respiratory, alimentary, renal, urinary or gastrointestinal system. All of these systems are affected one way or the other by the Endocrine system.

The Endocrine System also known as the hormone system is responsible for the hormones like Progesterone, Oestrogen, and Thyroid Hormones among many. These hormones are particularly high during the first trimester and for a very good reason.

Progesterone is an important hormone that prepares your uterus for the egg to implant properly. It is also however responsible for the mood swings that come with pregnancy. Progesterone also acts as a muscle relaxant to prevent you from contractions and onset of early labour. However, progesterone with its muscle relaxant is also responsible for slowing down digestion in turn causing constipation.

Speaking of gastrointestinal changes, another symptom that occurs is gastroesophageal reflux (GERD). This happens because of the increased pressure of the growing fetus. Along with GERD, nausea and vomiting, commonly known as “morning sickness” also begin. The cause for this unknown but it correlates with the increase in the level s of progesterone, and another hormone known as human chorionic gonadotropin (hCG) which is responsible for the growth of the baby throughout pregnancy. To tackle the morning sickness, Click here.

Oestrogen maintains the lining of the uterus which is vital for the baby’s development. It is also known to increase blood flow which can have both pleasant and un-pleasant reactions. The increased blood flow is maybe what gives pregnant mothers the “pregnant glow” but it also makes the breast tender with ache.

As the blood flow is increasing due to progesterone, the blood vessels are dilating which causes blood pressure to decrease. In response to this, the cardiac output increases up to 20%. Meanwhile, sodium and water retention also occur causing swelling or oedema which in turn causes the total blood volume to increase.

If a mother already suffers uncontrolled high blood pressure, she is likely to suffer from a pregnancy complication called pre-eclampsia which also causes oedema thus masking the real issue. Close monitoring in such a case and detection of protein in the urine can distinguish the condition better and earlier to prevent any harm to the baby or the mother.

Thyroid Hormone like T3 and T4 also slightly increase in the first trimester of pregnancy along with Thyroxine- binding globulin (TBG) due to rise in oestrogen. This increase help support the neurodevelopment and bone development of the baby.

These are a gist of changes that occur in a pregnant mother’s body during the first trimester of pregnancy. And all of these changes have one and only one goal – support and maintain the growth and development of the foetus. And these first 3 months are as crucial for the mother as they are for the baby.

Now that we understand what changes occur in the mother’s body, what happens to the foetus’s growth?

Why are these first three months of pregnancy important?

The first trimester of pregnancy begins from conception up until 12 weeks i.e., the first 3 months of this beautiful 9 months journey. Now if you are not planning your pregnancy, it is most likely that you would not realize you are pregnant up until week 5 or 6. Till that time, the foetus would have developed quite a bit. In this lag of time if the mother is facing any nutritional deficiencies, then that will most definitely contribute to improper growth and development of the baby. So, what needs to be done to prevent that?

For that we need to understand how nutrition plays an important role in the first trimester of pregnancy?

Let’s find out!

In the first month of pregnancy that is week 1 to week 4 a lot is happening.

  • The fertilised egg is growing slowly. Amniotic sac forms around and cushions the growing embryo. An organ called the placenta also develops.
  • Placenta is a source of transfer of nutrients or you could say a food source from the mother to the foetus.
  • The mouth, lower jaw, and throat of the foetus are also developing.
  • In this this phase the immature cells of the body take on individual characteristics and reach their mature form. Blood cells are also taking shape and circulation starts to begin.

You must be thinking, how does nutrition come into picture? Well, all these developments in growth require certain nutrients to function well. Those include Vitamin A, Vitamin B6, Vitamin B12, Folic Acid, Iron, Zinc, Copper and Methionine. All these nutrients are necessary for placental growth, cell maturity, cell growth, Reb Blood Cell (RBC) synthesis, DNA and protein synthesis. Deficiencies in these nutrients in the first month of pregnancy may hamper the build blocks of growth and development for the child.

In the second month of pregnancy that is week 5 to week 8,

  • The facial features continue to develop.
  • Ears, arms, legs, fingers, toes and eyes are beginning to be formed.
  • The digestive tract begins to develop, bones become stronger, the head is proportionate to the body and heartbeat is usually detected.
  • Most importantly, the neural tube that involves the brain, spinal cord and other nervous tissue is being well formed at this time.

A lot of nutrients are required at the moment like Vitamin A, Vitamin K, Vitamin D, Calcium, Phosphorus, Magnesium, Iodine, and Iron. All with important roles and function. But certain nutrients have a more focused role in the brain and neural tube development. In this phase deficiency of nutrients like Folic Acid, Zinc, Choline, Omega 3 especially DHA and EPA can affect brain development and may cause neural tube birth defects in the foetus. This can be easily prevented by having proper pre-natal or pre-pregnancy nutrition of the mother.

In the third month of pregnancy, that is week 9 to week 12,

  • The arms, legs, fingers and toes are getting fully formed.
  • Fingernails, toes, external ears, teeth are also getting developed.
  • The reproductive organ starts developing, circulation and urinary tract are working, liver is also doing its functions.
  • By the end of the third month, the foetus is fully formed and will continue to develop.

By this phase, Protein becomes very essential for the foetus as well as the mother. All the nutrients required in the first 2 months are as equally essential in the third month.

The foetus gets all these nutrients from the mother. Which means she requires more nutrients than she passes on to her baby so that her body functions well as well.

With all these important nutrient requirements, one must wonder how much should a pregnant woman consume? Well, she is having a growing developing foetus inside her that needs essential and nutritious food. Would you say she is “Eating For Two?”

NO! that in fact is a myth that a pregnant woman should eat for two – herself and the baby. Let me explain why!

Pregnant women do require more nutrients than non-pregnant women. But the requirements are certainly not double of what she usually eats. So, what are the nutritional requirement of a pregnant woman?

Let’s compare the nutrient requirements of a pregnant and non-pregnant woman, according to Indian Council of Medical Research and National Institute of Nutrition, 2020:

Calories1600-2700 kcals (depending on physical activity)+350 kcals on normal requirement
Protein0.8-1 gram per kg body weight+ 9.5 grams on normal requirement
Magnesium370 mg/d440 mg/d
Zinc13.2 mg/d14.5 mg/d
Iodine140 mcg/d220 mcg/d
Folic Acid220 mcg/d570 mcg/d
Vitamin B122.2 mcg/d+0.25 mcg/d
Vitamin A840 mcg/d900 mcg/d

What would happen if a pregnant woman is eating for two?

During pregnancy every woman gains a few extra kgs in weight. An increase in about 10 kgs throughout the pregnancy is completely normal. This normal and healthy weight gain happens due to the growing foetus as the increase in the required nutrients to sustain the pregnancy.

But, if the woman eats in the intention of eating for two, she may be eating way more than what is required for her and the baby. This may affect the mother in ways like:

  • The mother may fall in the obese category of BMI,
  • Increase the risk of gestational diabetes,
  • Hypertension known as pre-eclampsia may occur,
  • Sleep apnoea which is a sleeping disorder in which the breathing suddenly stops and starts and
  • She may also increase the chance of a C-section.

The baby on the other hand may be born with:

  • Hypoglycaemia – Low blood sugars,
  • Baby may be overweight or large in size than required,
  • There may be an increase chance of C-section and
  • The risk childhood obesity.

So, what should a mother do in these conditions? What foods should she eat? Or what foods should she avoid?

As discussed before there are a lot of nutrients that an expecting mother requires in the first 3 months of her pregnancy. In order to achieve the correct amount of nutrition, she should make sure to incorporate all those nutrients in her daily diet.

So, here we go!

It is a lot to take in I’m sure, which is why it is equally important to understand the requirement of a new pregnant mother. If you are one or taking care of one, be patient, loving and nurturing not only for the baby growing inside of the womb but also to the mother who is doing it all😊


Soma‐Pillay, P., & Catherine, N. (2016). P, Tolppanen H, Mebazaa A, Tolppanen H, Mebazaa A. Physiological changes in pregnancy. Cardiovasc J Afr27(2), 89-94. Kraschnewski, J. L., & Chuang, C. H. (2014). “Eating for two”: excessive gestational weight gain and the need to change social norms. Women’s Health Issues24(3), e257-e259. Williamson, C. S. (2006). Nutrition in pregnancy. Nutrition bulletin31(1), 28-59. Burton, G. J., Hempstock, J., & Jauniaux, E. (2001). Nutrition of the human fetus during the first trimester—a review. Placenta22, S70-S77. ICMR-NIN Expert Group on Nutritent Requirement for Indians, Recommended Dietary Allowances (RDA) and Estimated Average Requirements (EAR) – 2020.

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