Most people know that smoking increases cancer risk, especially lung cancer. However, the impact of smoking during pregnancy on gestational diabetes is not frequently discussed. Smoking among pregnant women is a major concern as it leads to health problems for both the mother and the child. Therefore, smoking is a risk factor for gestational diabetes. 

What is gestational diabetes?

Gestational diabetes, or diabetes during pregnancy, is associated with high blood sugar levels as your body can’t make enough insulin during pregnancy. Due to the hormonal changes and weight gain associated with pregnancy, pregnant women may experience some amount of insulin resistance.

Risk factors for gestational diabetes

1. Advancing maternal age

2. Maternal obesity

3. Smoking

4. Excessive alcohol intake

5. Maternal short stature

6. Genetic predisposition to type 2 diabetes mellitus and gestational diabetes mellitus

Prevalence of gestational diabetes

Research conducted on pregnant women shows that the prevalence of gestational diabetes was 19.8% in non-smokers, 24.3% in smokers who quit, and 26.6% in those who continued smoking till the first trimester. Chronic smoking increases insulin resistance by directly affecting insulin-mediated glucose uptake, pancreatic β-cell function, and insulin secretion.

Impact of smoking on the mother and baby's health

Smoking during pregnancy increases the risk for severe pregnancy complications such as preterm birth, perinatal mortality, and stillbirth, low birth weight offspring. Compared to non-smoking mothers, women who smoked in the first trimester of pregnancy gave birth to babies with lower birth weights.

Smoking also reduces the delivery of oxygen to the fetus, creating a greater demand for oxygen in the maternal body and increasing fetal and maternal stress. The baby is prone to develop respiratory illnesses later in life if the mother has been a smoker during pregnancy. Moreover, smoking during pregnancy is associated with a high risk of premature bleeding and other complications. Here's how smoking can affect different health determinants:

1. Post-food glucose concentration

In pregnant women with gestational diabetes, 1-hour post-eating concentrations of glucose were higher. 2-hour post-eating concentrations were lower in women who smoked at the beginning of their pregnancy than non-smokers.

2. Oral glucose tolerance test

Compared to non-smokers, women who continued smoking after the first trimester had higher fasting and 1-hour glucose concentrations. Women who stopped smoking after the first trimester also had higher fasting glucose concentrations but not higher 1-hour glucose concentrations. Chronic cigarette smokers have lower insulin sensitivity compared with non-smokers.

3. HbA1c level

HbA1c is a test that measures the average blood sugar level over the past 3 months. The HbA1c test is commonly used to diagnose type 2 diabetes and prediabetes. HbA1c was found to be higher in heavily smoking pregnant women.

Former smokers and current smokers with gestational diabetes require higher amounts of insulin compared to non-smokers. Pre-pregnancy smoking is also associated with an increased risk of gestational diabetes. 2 pack-years of smoking (a pack-year is the number of packs of cigarettes smoked per day multiplied by the number of years the person has been smoking) can increase gestational diabetes risk by 50%. Smoking reduces HDL cholesterol or good cholesterol and increases triglycerides leading to an increased risk of obesity.

Smoking cessation is encouraged among pregnant women, as it reduces cardio-metabolic risk factors and improves blood sugar levels in people with gestational diabetes.


Smoking is associated with adverse outcomes on maternal and child health. It also increases the risk of gestational diabetes and negatively affects blood glucose regulation of the body leading to insulin resistance in the pregnant woman. Smoking cessation reduces the risk of diabetes and cardiovascular disease and is thus encouraged in pregnant women to avoid the adverse effects of smoking. For more such information, head to the Medkart website today!


1. Does smoking affect gestational diabetes?

Smoking can increase the risk of developing gestational diabetes. Mothers who continue to smoke after the first trimester have babies with low birth weight.

2. Can smoking during pregnancy lead to diabetes in the baby?

A study showed a 4 fold higher risk of type 1 diabetes among children whose mothers smoked 10 or more cigarettes per day during pregnancy.

3. What are the risks associated with smoking during pregnancy?

Smoking during pregnancy might increase the chances of:

• Low birth weight of the baby

• Lung diseases in the baby

• Miscarriage

• Stillbirth

3. Can smoking affect gestational diabetes testing?

Yes, the oral glucose tolerance test showed higher fasting glucose levels and higher glucose levels in the 1-hour glucose tolerance test, indicating low insulin sensitivity in smokers.