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Gestational Weight Gain: Know How It Adversely Affects You and Your Baby

Gestational weight gain is defined as the amount of weight you gain from the commencement of your conception to the time just before the birth of the infant.

During this period, you will undergo many changes both biologically and physiologically.

The Institute of Medicine (IOM) has issued guidelines in this respect in the year 2009, specifying the range of acceptable weight gain based on your pre-pregnancy BMI.

Adhering to those guidelines is in the interest of your pregnancy and the birth of your child.[1]

In the light of uncontrolled weight gain during gestation, we need to learn about the various possibilities, related issues and their ill-effects to be better prepared.

In this article, you get to know about the various aspects of gestational weight and its effects on the physiology, metabolism and other hormonal and biological developments.

You also get an insight into the different aspects of gestational weight gain and its short and long term impact on your life.  

Gestational Physiology

The gestation period in a woman causes many physiological and metabolic changes besides the more evident biological changes.

The enhanced hormonal secretion induced by the active endocrine glands is a normal consequence of gestation. This is directly related to the development of the fetus and the placenta.

stages of pregnancy

You must understand that it is natural for women to gain weight during gestation. However, weight gain should be within recommended standards for better health.[2]

1. Gestational cardiovascular changes:

Your cardiac activity rises during your gestation. As your pregnancy progresses, the heart rate also increases.

Your blood circulation too is impacted.  This is manifested in an 18 per cent increase in the red blood cell mass during your gestation.[3]

2. Gestational renal changes:

During the early stages of pregnancy, there is a marked increase in renal plasma flow and glomerular filtration rate.

This leads to a gestational weight gain which is explained by the additional body water in a pregnant woman. The amniotic fluid is most of this water by volume along with the placenta. Even the fetus which is mostly composed of water (75 to 90%) adds to the body weight. [4]

3. Gestational endocrine changes:

The hyperactive endocrine glands during the onset of gestation cause metabolic adaptations. In the first trimester, you encounter a rise in chorionic gonadotropin (a hormone that controls reproductive activity) in your blood and urine.

At the same time, your adrenal cortex becomes additionally active.

Whereas during the last trimester, progesterone, estrogen and the adrenocortical hormones are more pronounced and there is a definite impact on your gestation.[5]

4. Gestational metabolic changes:

Many of the metabolic changes in your body during gestation are determined on how your fetus reacts to its nutritional demands.

You are likely to feel increased appetite in the early stage of gestation.  Other adjustments are triggered by the placental needs and the enhanced hormonal activity.[6]

Gastric motility (digestion process) is affected by the increased presence of progesterone.[7]

Suggested weight gain

The 2009 IOM pregnancy weight gain chart defines the quantum of acceptable gestational weight with respect to your pre-pregnancy BMI.  This enables you to place yourself in the right category and adopt measures to your benefit. This is a broad chart to be used as a base guideline:

Pre-pregnancy BMI

BMI < 18.5 (Underweight) Acceptable gain 12.5 to 18 kg
BMI 18.5 to 24.9 (Normal weight) Acceptable gain 11.5 to 16 kg
BMI 25.0 to 29.9  (Over weight)   Acceptable gain 7.0 to 11.5 kg
BMI > 30 (Obese)       Acceptable gain 5.0 to 9.0 kg

This is the overall guideline for the quantum of acceptable weight gain in the case of a single pregnancy.  This can be further broken up into the three trimesters.

1st Trimester: 0 to 700gms per month for a total of 500 to 2 kg.

2nd Trimester: 500gms per week for a total of 5.5kg to 6.5 kg.

3rd Trimester: 400gms to 500gms per week for a total of 4.5kg to 6.5 kg.[8]

Distribution of the pregnancy weight:

The weight that you gain during the period of pregnancy is distributed on an average in the following manner:

Pregnancy Weight

1. Fetus:

The approximate fetus weight can be between 3.1kg to 3.6kg. It is not possible to perfectly ascertain the weight of the fetus. Since it is influenced by multiple dynamics, the space to measure fetal growth is limited.

Your physiology and metabolic activity coupled with habits and living pattern are key determinants of the fetal weight.

2. Placenta:

The placenta can weigh approximately 700gms. The placenta mass and fetal weight during the stages of gestation are interrelated. With increased age of gestation, the placental mass shows significant growth pattern, matching its ratio with fetal growth.

3. Amniotic fluid:

Amino fluid can weigh up to 900gms. During gestation, there is significant volumetric variation. By the 33rd week of gestation, the amniotic fluid reaches its maximal volume.

The four major flow sources in the amniotic fluid movement during gestation are fetal urine, lung secretion, fetal swallowing and intra-membranous absorption.

Apart from this increased fluid and blood quantity can weigh between 1.3kg and 1.8kg each. Similarly, bloated uterus and breasts can weigh 900gms each. Additionally, massed fat and proteins can weigh between 2.7kgs and 3.6kgs.[9]

Effects of Gestational weight gain

Now that we know about gestation weight gain pattern and the acceptable range, we also need to analyse the consequences of excess weight gain.

The general broad ill effects and risks are tabulated below:

  • You may need a caesarian section.
  • You may suffer from postpartum weight retention.
  • The infant born will carry the risk of macrosomia (baby being larger than average) and child obesity.

If the gestational weight gain is inadequate, the infant will carry the risk of preterm birth and be small for gestational age. As for the mother, she may fail to initiate breastfeeding.[10]

Consequences of GWG during pregnancy

IOM suggests that gaining 11 to 12 kgs during pregnancy is normal but anything beyond that can cause problems to both the mother and infant.

Below are the consequences of excessive gestational weight gain.

1. Gestational Diabetes:

When you gain weight beyond the acceptable range, you are prone to suffer gestational diabetes. Overweight pregnant women encounter higher levels of ketones and ketonuria.

On the bright side, this is temporary and disappears as soon as the baby is born. However, once you suffer from gestational diabetes, you may suffer the same fate in your future pregnancy as well.

The most disconcerting fact is that you may develop type2 diabetes in the later stages of your life.[11]

2. Experience a difficult pregnancy:

Excessive weight gain can cause leg cramps, backache, exhaustion, joint pains, and heartburn. This makes the body bear additional pressure, restricting the circulation of blood and fluids inside your body.

3. Gestational hypertension:

If you are overweight or weight before conception, you are more likely to acquire gestational hypertension. However, the overall increase of hypertensive disorder with respect to the gestational weight gain is not clearly established (IOM, 1990).[12]

4. Delivery complications:

Your gestational weight gain beyond acceptable limits directly affects the delivery of your child.

You are more likely to be recommended caesarean considering the health of both the mother and the child. By gaining weight, you are passing some of it to the fetus.

The size of the fetus will preclude your chances of delivering your child vaginally. The only alternative would be a caesarean. Caesarean also delays lactation and your post-delivery recovery.  

5. Maternal mortality:

Though this would sound too pessimistic, the size of the baby due to uncontrolled gestational weight gain makes your labour and delivery a difficult one.

The mortality rate of the mother and the infant increases manifold, especially where optimal obstetric facilities are lacking.

6. Inadequate lactation:

Apart from the delayed lactation in case you have to undergo c-section, you have to deal with a lower rate of lactation and the duration of the breastfeeding of your child is drastically reduced.  

So your reduced lactation resulting from gestational weight gain in excess will surely affect the nutrition of your child.

7. Weight retention:

Your postpartum weight is your weight post-delivery of your child. The weight of the fetus, placenta and amniotic fluid is shed once the term is over and the plasma volume returns to your pre-pregnancy values, your weight is thus greatly reduced.

If your gestational weight gain has been excessive, you cannot lose this weight quickly and returning to the normal weight can take months.

Postpartum weight retention will move you into a higher BMI category, which will affect your future pregnancies.[13]

8. Mental health:

Both the gestational and postpartum mental state is adversely affected if you are overweight. The difficulties encountered during and post-pregnancy may cause depression.[14]

Long term consequences of gestational weight gain:

IIn the long term, there are certain health issues associated with gestational weight gain, both for you and your child. Some of the medical conditions are serious enough to be considered mentioned below:

  • Metabolic disorder:The biological and physiological changes that you undergo during pregnancy, causes metabolic changes later in life. Your uncontrolled gestational weight gain would result in postpartum weight retention.[15]
  • Cardiovascular health issues:The excess gestational weight gain makes you prone to cardiovascular disorders later in life. Obesity is the direct cause of increased blood pressure, raised cholesterol level with risk of heart attacks and stroke.[16]
  • Risk of Cancer:Chances of developing breast cancer are higher if pre-menopausal gestational weight gain exceeds 16 kg and an increase in the BMI index is greater than 7.[17]
  • Impact on your baby:Your excessive gestational weight gain will result in the birth of an overweight baby. It is suggested that the child will carry a greater risk of diabetes and obesity all through childhood and beyond. The hazards the child will face in life due to this medical condition is well imaginable.[18]

Pregnancy in women is a natural biological process. The changes and adjustments in the body is a normal phenomenon that triggers the biological and physiological activity that impacts the process of gestation and childbirth.

These changes require you to be conscious of health needs, especially weight management since it not only influences your health but your child’s health too.

Q: Is weight gain during gestation inevitable?

Gestational weight gain is not only inevitable but also absolutely normal. However, it should be within the limits recommended by IOM.

Q: Does gestational weight gain adversely affect you?

When it exceeds the acceptable range, you are prone to face the consequences, most of which are hazardous to your health as well as that of the fetus.

Q: Does gestational weight gain have long term consequences?

If your weight gain during pregnancy is in the normal range, most of the health issues that crop up are temporary and disappear at the end of the term. If you have gained excessive weight, you are prone to carry the hazards well into your future.