In pregnancy, a healthy diet that includes an increased amount of energy, protein, vitamins, and minerals is required to meet the demands of both the mother and the child.

Increased nutritional needs coupled by some pregnancy conditions (hyperemesis, eating disorder, dietary restrictions, lack of support, etc.) may render dietary intake insufficient and may leave expectant mothers in a malnourished state.

Nutrient Deficiencies in Pregnancy

Nutrient deficiencies occur when the amount of essential energy, vitamins, and minerals, which are typically obtained from the diet, are not enough to meet recommended daily requirements for proper health, growth, and development.

During pregnancy, lacking important nutrients can have grave consequences. To give an example, low levels of iodine, iron, folate, calcium, and zinc can cause anemia, pre-eclampsia, hemorrhage, and even death.

Nutrient deficits can also lead to stillbirth, low birth weight, and developmental delays for children according to studies. Increasing evidence even suggests that the outcome of fetal nutrition may persist well into adulthood, even with the possibility of intergenerational effects.

Despite a great deal of evidence supporting the importance of adequate nutrition in pregnancy, around 20% to 30% of pregnant women worldwide still suffer some vitamin deficiency. Vitamin B12 insufficiency alone is proposed to affect 25% of pregnancies worldwide. Due to this, a number of studies were published over the last few years about supplementation; however, legal and moral issues surrounding pregnancy limit these studies and cause reservations due to uncertainties.

Supplementation During Pregnancy

A healthy, diverse diet is still the preferred means to match up to the intake requirements but some nutritional needs in pregnancy are challenging to meet with diet alone. In those cases, supplement use may be prescribed.

Even the World Health Organization (WHO) updated their recommendation on multiple micronutrient supplementation (MMS) in pregnancy from “not recommended” to “recommended in the context of rigorous research”. In their comprehensive antenatal care (ANC) guideline updated in 2020, they state that its full benefit is still difficult to conclude.

In a study on antenatal supplementation, balanced energy and protein intake reduced the risk of stillbirth and small-for-gestational-age. Vitamin D and calcium supplements support fetal growth and bone development as well as ensure optimal maternal stores and prevent hypertensive disorders. Aside from folate and iron-rich diets, iron and folic acid supplements are important for preventing anemia and neural tube defects, respectively.

Though further research is required about supplementation, deficiencies in vitamin B complex during pregnancy is correlated to increased risk of neural tube defects, preeclampsia, congenital heart defects, placental abruption, preterm delivery, and low birth weight in infants, among others.

Supplementation with polyunsaturated fatty acids (PUFA) may improve neonatal outcomes and prevent preterm birth, especially in high-risk pregnancies, but they can also slightly increase the chance of post-term pregnancies and large for gestational age (LGA).

Evidence regarding the importance of these nutrients in pregnancy is continually evolving. Given the potential risks associated with deficiencies, supplementation is most likely to be considered. Nevertheless, current knowledge is limited to confirm the full benefits of supplements during pregnancy and further study is required.

Are All Supplements Beneficial for Pregnant Women?

Additional vitamin A is needed during pregnancy to support fetal growth and tissue development but too much of this can cause harm. An upper limit of 10,000 IU per day (3000 µg retinol) has been established because retinol is associated with teratogenic effects and the non-toxic form (beta-carotene) is preferred during pregnancy. In deficient women, supplementation may be initiated after careful assessment and monitoring.

Studies do not support routine vitamin E supplementation, alone or in combination with vitamin C, for the prevention of any unwanted fetal outcome. Rather, it was associated with an increased risk of self‐reported abdominal pain and term prelabour rupture of membranes (PROM).

Oral Supplementation May Not Be Enough

Despite vitamin supplementation, deficits still exist. A study done on healthy pregnant women, taking a good diet and supplemented with vitamins showed a high percentage of vitamin A, B6, niacin, thiamin, and B12 hypovitaminemia. Some were noted to worsen in later trimesters.

Optimizing oral intake may not always be achievable in some pregnant women. When weight loss is over 5% or continuous weight loss is experienced, parenteral nutrition (PN) may be ideal to ensure she receives adequate nutrition.

Intravenous Nutrition for Pregnant

PN has shown to be a relatively safe and effective way to support those who cannot utilize their gastrointestinal tract well. Following a series of ultrasounds, fetal findings improved significantly on intravenous nutrition according to a study.

Intravenous nutrition in these cases not only treats the chronic dehydration but also malnutrition. This may include the administration of vitamins, minerals, amino acids, and other essential nutrients by intravenous infusion. This may reduce the risk of adverse maternal and fetal effects.

It is best to administer nutrient replacement prior to depletion. Depending on the severity, scheduled infusions may be required. Careful calculation of pregnant womans’ requirements by a professional is always advised. Individualized care plans, administration, and management under the watchful eyes of highly skilled clinicians can prevent the occurrence of complications that can be life-threatening for the mother and her child.


The importance of maintaining a healthy diet before and during pregnancy should not be underestimated. Nutritional deficiencies during pregnancy can reap not only short-term but long-term damage. Supplementation may be prescribed depending on the need but individualized, professional care is a must to prevent untoward complications.

Further, large-scale studies will be beneficial to shed more light on the effectiveness and potential impact of nutritional supplementation across different pregnancy stages, improving these outcomes.


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Gete, D. G., Waller, M., & Mishra, G. D. (2020). Effects of maternal diets on preterm birth and low birth weight: a systematic review. The British journal of nutrition, 123(4), 446–461. https://doi.org/10.1017/S0007114519002897

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