Unhealthy Weight and Pregnancy

Unhealthy weight gain. However, unhealthy weight increases the risk of many health conditions including hypertension and diabetes, and avoiding the subject of unhealthy weight gain misses an opportunity to possibly prevent or treat many weight related illnesses. The continued rise in obesity and related diseases is of global concern, and has prompted the American College of Obstetricians and Gynecologists (ACOG) to recommend that the body mass index BMI be recorded for all women at the initial prenatal visit, and that Information concerning the maternal and fetal risks of a very elevated BMI in pregnancy should be provided.

The body mass index (BMI) is a measure of someone's weight in relation to their height. The BMI is equal to a person's weight divided by their height (BMI = kilograms /meters 2)
. The greater a person's weight is for a given height the higher their BMI will be. The BMI is used to screen persons for weight categories that may lead to health problems.
BMI Category
= <18.5 Underweight
= 18.5-24.9 Normal weight
= 25-29.9 Overweight
30 -34.9 Obese- Class I
35 - 39.9 Obese- Class II
40 and above Obese- Class III
Normal BMI (18.5 - 24.9)
Height  (feet,inches) weight
4' 10" 91 - 119
4' 11" 94- 124
5' 0" 97-128
5' 1" 100-132
5' 2" 104-136
5' 3" 107-141
5' 4" 110-145
5' 5" 114-150
5' 6" 118-155
5' 7" 121-159
5' 8" 125-164
5' 9" 128-169
5' 10" 132-174
5' 11" 136-179
6' 0" 140-184
6' 1" 144-189
6' 2" 148-194
6' 3" 152-200
6' 4" 156-205

The table to the left shows the healthy weight range for persons of different heights.

Over the last 20 years the number of women with an unhealthy BMI has increased greatly. In 2003, 1 in 5  U.S. women of reproductive age (aged 18-44 years) were obese (BMI greater than or equal to 30) . There is good evidence that women with a high body mass index (BMI > 30 ) before or during pregnancy are at greater risk of complications in pregnancy including:

  • Birth defects such as heart defects, neural tube defects, and other abnormalities.
  • Difficulty seeing all of the baby's organs and estimating the baby's weight with ultrasound.
  • Difficulty monitoring the  baby's heart rate tracing with  the fetal heart monitor
  • Gestational diabetes 
  • Pre-eclampsia (high blood pressure with protein in the urine).
  • Problems having epidural and other anesthesia.
  • Delivery by emergency caesarian section.
  • Heavy bleeding after delivery.
  • Increased risk of forming abnormal blood clots.
  • Bladder and kidney infections.
  • Wound infection
  • Large babies with birthweight above the 90th percentile
  • Less likely to have successful vaginal birth after cesarean section
  • Increased risk of stillbirth.

The level of these risks increases as the mother's BMI increases .

In view of the above risks the American College of Obstetricians and Gynecologists (ACOG) has recommended :

  • Preconception counseling for obese women who are planning a pregnancy.
  • BMI should be recorded for all women at the initial prenatal visit.
  • Information concerning the maternal and fetal risks of obesity in pregnancy should be provided
  • Overweight women (BMI 25-29.9) should be advised to gain no more than 15 to 25 pounds during pregnancy, and obese women (BMI = 30) no more than 15 pounds during pregnancy.
  • Obese women should be offered nutrition consultation, and they should be encouraged to follow an exercise program. This should be continued after delivery.
  • Screening for gestational diabetes at the initial prenatal visit with repeated screening later in pregnancy if the results are negative.
  • Women with a BMI of 35 or greater who have preexisting medical conditions, such as hypertension or diabetes, may benefit from a cardiac evaluation.
  • Consultation with anesthesiology prior to delivery.
  • Use of graduated compression stockings, hydration, and early mobilization during and after cesarean delivery should be encouraged.
  • Consultation with weight loss specialists before attempting another pregnancy

As noted above the American College of Obstetricians and Gynecologists (ACOG) recommends women at an unhealthy weight should be offered both nutrition consultation and an exercise program. Although physical activity alone produces only a modest reduction in weight compared with dieting alone regular physical activity helps maintain weight loss and results in many health related benefits in patients even if they lose no weight  .

Most patients who are overweight can begin with activities such as walking starting with a 5 minute work out and gradually working up to their goal over many weeks. However, patients who have known coronary, metabolic, pulmonary disease, or signs or symptoms suggestive of coronary heart disease (CHD) may benefit from diagnostic exercise testing before beginning an exercise program.

Lastly, breast feeding can help patients to lose the weight gained during pregnancy,  and may also have a small protective effect against childhood obesity


See OBFOCUS .com: BMI and Pregnancy

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