Obesity and Pregnancy

Obesity is based on body mass index (BMI) and is further identified by weight in kilograms divided by height, in meters, squared (kg/m2).

Image 1:
Body Mass Index (BMI)

Even before pregnancy, women with obesity are at risk of menstrual dysfunction, including oligo-ovulation or anovulation, which could lead to difficulty conceiving (Creanga et al., 2022). In fact, the prevalence of anovulation is three times as high as that among women of normal weight (Creanga et al., 2022).

Once a woman is pregnant, there are additional risks that she has that are associated with obesity. First, women with obesity have a significant increase in early pregnancy loss (Ramsey & Schenken, 2024). Spontaneous abortion is more likely to occur in women with obesity and in women with recurrent miscarriage (Ramsey & Schenken, 2024). In fact, for women who have suffered from recurrent miscarriage, obesity almost doubles the risk for future miscarriage (Ramsey & Schenken, 2024).

Diabetes is another complication that can affect a pregnant woman. A woman with obesity, without recent testing, may have undiagnosed type 2 diabetes. Gestational diabetes, or diabetes that has an onset during pregnancy, is three to four times more likely in obese women (Creanga et al., 2022). Gestational diabetes and type 2 diabetes can lead to additional maternal and fetal complications (Creanga et al., 2022).

Obesity is also a risk factor for gestational hypertension and preeclampsia. Inflammation and increased insulin resistance may have a role in the increased risk of preeclampsia and gestational hypertension (Creanga et al., 2022). Both of these conditions can lead to maternal and fetal complications.

Image 2:
Preeclampsia

(*Please click on the image above to enlarge.)

Preterm birth is also a risk of obesity. This risk is not usually due to spontaneous preterm labor but medically indicated preterm delivery due to maternal medical reasons (Ramsey & Schenken, 2024).

In addition, obstructive sleep apnea worsens with obesity and weight gain in pregnancy, leading to increased complications for the woman (Ramsey & Schenken, 2024).

During the labor and delivery timeframe, obesity has been known to contribute to longer inductions of labor, longer labor times, and increased rates of cesarean sections (Paredes et al., 2021). Women with obesity are less likely to have a successful trial of labor after a cesarean section.

Women with obesity are also more likely to have a macrosomic infant, which is defined as an infant weighing greater than 4000 grams. Macrosomia can cause many delivery complications, including (Ramsey & Schenken, 2024):

• An operative vaginal delivery (requiring forceps or a vacuum)
• Perineal lacerations
• Cesarean section

Image 3:
Operative Vaginal Delivery Methods: Forceps vs. Vacuum

As previously discussed, gestational diabetes is a risk of women with obesity. Gestational diabetes is strongly correlated with and a well-established risk factor for fetal macrosomia (Salameh et al., 2023). In addition, it has been determined that the presence of gestational diabetes and maternal obesity together can even further increase the risk of fetal macrosomia than the individual risk factors alone (Salameh et al., 2023). Macrosomia is a problem that can affect the mother and fetus during delivery. Infants born to women with obesity also have an increased risk of hyperinsulinemia and hypoglycemia.

Image 4:
Gestational Diabetes

(*Please click on the image above to enlarge.)

Macrosomia can cause many complications for the infant too including (Ramsey & Schenken, 2024; Bai et al., 2023):

• Birth fractures
• Shoulder dystocia
• Hypoglycemia
• Physical growth and development delay

As children of women with obesity age, they are more prone to childhood obesity and metabolic disorders. Congenital deformities such as neural tube defects, cardiovascular anomalies, and omphalocele occur at an increased rate in a child delivered to a woman with obesity (Kim & Ayabe, 2023). Fetal, neonatal, and infant death are also more common for children born to women with obesity (Ramsey & Schenken, 2024).

Weight loss is the most important factor in improving outcomes. Making adjustments to diet and exercise level before getting pregnant can improve reproductive and pregnancy outcomes and improve the woman's overall health (ACOG, 2021).

A 10% reduction in pre-pregnancy BMI can positively impact outcomes. Weight loss surgery prior to pregnancy may also be beneficial. Weight loss drugs should not be used during pregnancy. Weight gain during pregnancy should be less and appropriate weight gain recommendations will vary depending on the severity of obesity (Ramsey & Schenken, 2024).

Early screening for diabetes is recommended, and close surveillance of the woman and the fetus during pregnancy is important. A consultation with a dietician can help the woman to make healthy choices before and during pregnancy. As mentioned, limiting weight gain but also increasing exercise once pregnancy occurs, can also lead to better outcomes as well (Ramsey & Schenken, 2024).

The Institute of Medicine (IOM) has shared clinical recommendations for appropriate weight gain parameters for women with obesity. Their recommendations for optimal gestational weight gain, or GWG, is 11 to 20 pounds for women with a BMI ≥ 30 (Kim & Ayabe, 2023).

An obesity-related risk for perinatal death that rises with gestational age has been reported (Ramsey & Schenken, 2024). Because the “mechanism” responsible for this is not known, standard fetal assessment and surveillance is recommended, rather than additional needs for women with obesity (Ramsey & Schenken, 2024). Once any woman is pregnant, it is important to assess fetal growth and well-being with ultrasound, nonstress tests, and biophysical profiles (Ramsey & Schenken, 2024). However, according to the American College of Obstetricians and Gynecologists (ACOG), weekly antenatal surveillance can be considered for women with a BMI between 35.0 to 39.9 kg/m2 starting at 37 weeks gestation and for a woman with a BMI of ≥40 kg/m2 starting at 34 weeks gestation (Ramsey & Schenken, 2024).

According to recommendations from the United States Preventative Services Task Force (USPSTF) that are also endorsed by ACOG, low-dose aspirin may be used in the second trimester to help prevent preeclampsia in pregnant women with obesity as well as additional risk factors such as multifetal pregnancy or chronic kidney disease (Ramsey & Schenken, 2024).

When caring for pregnant women with obesity, it is important not to judge the woman or make her feel guilty for being overweight but instead teach the woman about ways that she can make small, simple changes to improve her health outcomes (Creanga et al., 2022).

The nurse can help the woman identify barriers and find motivators to lead the woman to healthier eating and exercise. The nurse should be prepared for longer labor with possible complications, such as shoulder dystocia, vacuum, forceps, or cesarean section delivery during labor and delivery.

Once the woman has delivered, the nurse should watch for signs of infection and VTE. The nurse should also encourage breastfeeding, which can lead to additional weight loss for the woman and a decreased risk of obesity for the infant (Kim & Ayabe, 2023). The nurse should also teach these patients about the need for proper long-term medical care, including screening for diabetes, hypertension, and heart disease.

Claire is a 21-year-old woman who presents to the prenatal clinic at 19 weeks gestation for her first prenatal visit. She is 5'4," and her pre-pregnancy weight was 290 pounds, making her BMI 50.

Claire has not had regular preconception medical care up to now. She has not received any screenings at this point. She has gained 15 pounds since getting pregnant.

Claire’s vital signs are:

• Blood pressure: 108/68 mmHg
• Heart rate: 78 bpm
• Respirations: 16 bpm
• Temperature: 98.5 °F

Claire complains of excessive thirst, symptoms of a urinary tract infection, and fatigue.

What risks does Claire have?

Claire is at risk for all complications that are associated with obesity. She may be a type 2 or gestational diabetic considering her symptoms. She is at risk for gestational hypertension or preeclampsia, although her blood pressure is currently fine.

What care does Claire need?

Claire requires a full exam and screening for diabetes. Most importantly, she needs education on diet, exercise, and a healthy weight gain for obesity. She also needs to be taught the importance of keeping her appointments and closely monitoring the pregnancy for her and her baby's health. Claire also needs to know how important these things are and find the motivation to follow her care plan.

Obesity is a serious problem in the United States. It is not a problem that can be fixed overnight. Obesity can cause severe complications to both the mother and the fetus. Women require education regarding the risks and how to decrease them before getting pregnant. It is important that all nurses and healthcare providers know these risks and educate their patients appropriately.

• American College of Obstetricians and Gynecologists. (ACOG). (2021). Obesity in pregnancy: ACOG practice bulletin, number 230. Obstetrics and Gynecology, 137(6), e128–e144. Visit Source.
• Bai, W., Wang, H., Fang, R., Lin, M., Qin, Y., Han, H., Cui, J., Zhang, R., Ma, Y., Chen, D., Zhang, W., Wang, L., & Yu, H. (2023). Evaluating the effect of gestational diabetes mellitus on macrosomia based on the characteristics of oral glucose tolerance test. Clinica Chimica Acta, 544, 117362. Visit Source.
• Creanga, A. A., Catalano, P. M., & Bateman, B. T. (2022). Obesity in pregnancy. The New England Journal of Medicine, 387(3), 248–259. Visit Source.
• Kim, J., & Ayabe, A. (2023). Obesity in pregnancy. In StatPearls. StatPearls Publishing. Visit Source.
• National Heart, Lung, and Blood Institute. (NIH). (2022). What is venous thromboembolism? National Heart, Lung, and Blood Institute (NIH). Visit Source.
• Paredes, C., Hsu, R. C., Tong, A., & Johnson, J. R. (2021). Obesity and pregnancy. NeoReviews, 22(2), e78–e87. Visit Source.
• Ramsey, P.S., & Schenken, R.S. (2024). Obesity in pregnancy: Complications and maternal management. UpToDate. Retrieved January 17, 2024. Visit Source.
• Salameh, M.A., Oniya, O., Chamseddine, R.S., & Konje, J.C. (2023). Maternal obesity, gestational diabetes, and fetal macrosomia: An incidental or a mechanistic relationship? Maternal-Fetal Medicine, 5(1), 27-30. Visit Source.