Diabetes In Pregnancy: What Causes Stillbirth At Full Term?
Diabetes is becoming a common problem in pregnancy. There is an increased risk to the mother and baby both in cases of pre-existing diabetes and gestational diabetes (GDM). Any type of diabetes may be associated with the increased risk of still birth; which is defined as foetal death at or after 20 weeks of gestation. Approximately one out of ten pregnant women will be affected by diabetes and this will impose a heavy burden on health care providers.
The lifetime risk of getting diabetes in females born in the United States Of America in the year 2000 is estimated to be thirty nine percent which is roughly around one third of the population. So if there are hundred female births in the year 2000 then thirty nine of them may have diabetes during their life time and 10 of them may suffer from the disease during their fertile period. This estimate is based on the information received from the National Health And Nutrition Surveys (NHANES) conducted between 1984 to 2000. Obesity, sedentary life style and increased life span may be the probable causes of this epidemic of diabetes. The increased incidence of obesity has caused a reduced age of onset of diabetes. So the prevalence of diabetes in women of child bearing age has increased.
During the pre-insulin era in the early part of the twentieth century diabetes had a ninety percent mortality in infants and thirty percent maternal mortality. So before insulin discovery maternal death in a diabetic pregnancy was the primary concern despite the fact that foetal outcome was even worse. Even in the 1980's advice to avoid pregnancy in diabetic women was not very uncommon. After insulin discovery and use the risk to the mother was significantly reduced and medical care could concentrate more on the baby's outcome.
At present with good sugar control, improved foetal monitoring in utero, timely induction of labor and increased expertise in neonatal intensive care the outcome of babies has improved a significantly.
Global Prevalence of Diabetes Estimates for the year 2000 and projections for 2030
Risk Factors For Still Birth In Pre-Existing Diabetes
Type I Diabetes Or Insulin Dependant Diabetes Mellitus (IDDM)
This is the diabetes in which insulin is used from the beginning and serological markers of Islet Cell autoimmunity are present. It is therefore called IDDM (Insulin Dependent Diabetes Mellitus). There is a three to five times increased risk of still birth when compared to non diabetic pregnant women. Only one third of these still births have a explainable cause whereas in the remaining two thirds no specific cause may be found. There is a strong association between poor blood sugar control and bad outcome. Congenital birth defects and neonatal complications are the main cause of unfavourable outcomes. A glycosylated haemoglobin level (HbA1c) more than 7.5 % shows a poor blood sugar control level and is an independent risk factor for still birth.
Type II Diabetes Or Non Insulin Dependant Diabetes Mellitus (NIDDM)
If you are not prone to ketosis and do not require insulin for extended periods then it is Type II or Non Insulin Dependent Diabetes Mellitus (NIDDM). Here the risk of still birth is five times when compared to non diabetic pregnant women. Type II diabetes is more common than Type I diabetes and is responsible for even worse pregnancy outcomes. This higher pregnancy loss may be due to the association of this type of diabetes with obesity which itself is an independent risk factor for still birth.
It is important to note that these risk factors may not be exclusive to the type of diabetes and may be responsible for adverse outcome in all forms of diabetes.
Still Birth: Risk Factors In Diabetic Pregnancy
Prior Caesarean Section
Intrauterine Growth Restriction(IUGR)
Poor Blood Sugar Control
Systemic Lupus Erythymatosis(SLE)
Antiphospholipid Antibody Syndrome(APLA)
Big Baby & Birth Injury
Poor Socio-economic Status
Diabetes Diagnosis:Blood Glucose Levels
Fasting Plasma Glucose(mg/dl)
Oral Glucose Tolerance Test(mg/dl)
6.5 or above
126 or above
200 or above
5.7 to 6.4
100 to 125
140 to 199
99 or below
139 or below
At Least Two Of The Following Blood Glucose Values (mg/dl)
Fasting more than 95
1 hour more than 180
2 hour more than 155
3 hour more than 140
Risk Factors For Still Birth In Gestational Diabetes
It is the diabetes which develops during pregnancy. Gestational diabetes and type II diabetes share a common pathophysiological mechanism of insulin resistance resulting in the failure of the islet cell of pancreas. Both are considered to be the different stages of the same disease by some authorities. So GDM may represent a pool of both undiagnosed type II diabetic women who were diagnosed during pregnancy by routine screening and true cases of gestational diabetes who were not glucose intolerant before their pregnancy. The landmark Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) study did not show increase in perinatal mortality when it compared overt diabetes with hyperglycaemia of lesser magnitude. The HAPO study proposed to revise the diagnostic criteria for gestational diabetes because during pregnancy sugar levels less than those in other forms of overt diabetes were associated with adverse pregnancy outcome. So the cut off sugar levels for diagnosis of gestational diabetes are lower than other forms of disease (compare table 1 & 2 above). Some large population based studies have reassured that the risk of stillbirth is not increased in gestational diabetes, but there is sufficient evidence to prove that GDM does increase the risk of stillbirth It is important to understand that all forms of diabetes and not just gestational diabetes increase the risk of still birth.
A body mass index of more than 30 should be considered obese and it doubles the risk of still birth.
Cigarette smoking is the most common identifiable exposure.
Both these are modifiable risk factors.
Quitting smoking in the first trimester makes it similar to never smoked as per pregnancy outcome.
High blood sugar in mother causes a high blood sugar in the baby inside the uterus. This increased sugar stimulates the baby's pancreas to secrete insulin. Increased insulin secretion by the baby with increased supply of sugar from mother increases the baby's growth. This increased metabolic rate may be the cause of a lack of oxygen to the baby in the uterus and this hypoxia may be the cause of still birth.
Pre-pregnancy Care For Diabetics:Adapted from Temple (2011).
- Use of contraception until blood sugar level is within an optimal level of glycosylated haemoglobin (HBA1c).
- Diet and lifestyle modifications to maintain a healthy body weight and regular exercise.
- Smoking cessation and moderation in alcohol use.
- Supplementation with folic acid.
- Avoid medications like ACE inhibitors, statins and diuretics.
- Anti hypertensive medication to be substituted with labetalol or alpha-methyl dopa.
- Screening for and management of diabetic complications like retinopathy, renal disease or cardiac complications.
Foetal surveillance while still in utero is done by-
Foetal Kick Count- This is done by training the mother to identify foetal movements and making a kick chart.
Non Stress Test (NST)- It is based on a biophysical profile and amniotic fluid volume.
Umbilical Doppler + HbA1c (glycosylated haemoglobin) -It is also used to predict the risk of stillbirth.
Surveillance helps to reduce the risk because it helps in the identification of foetal distress and timely intervention to prevent foetal demise.
Timing Of Delivery
Expedite delivery if-
Poor compliance to treatment.
Poor glycemic control despite best efforts.
Bad Non Stress Test (NST)
Unfavourable biophysical profile
Baby weight more than 4.5 kg (Caesarean delivery may be required)
Self Blood Glucose Monitoring
A fasting blood sugar (after overnight fasting) level between 70-90 mg/dl.
Two hours after meals the desired blood sugar level is less than 130 mg/dl.
Aggressive sugar control by checking the blood sugar level using a glucose meter and titrating insulin dose accordingly helps to achieve better glycemic control.
The risk in diabetic pregnancy remains even with the best possible sugar control. A integrated approach and a team effort will help to reduce this risk to a great extent.
Do you think monitoring your blood sugar level by using a glucometer during your pregnancy helped to achieve a better sugar control?
Diabetic-Associated Stillbirth: Incidence, Pathophysiology, and Prevention Obstet Gynecol Clin N Am 34 (2007) 293–307
Donald J. Dudley, MD Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
The Increasing Prevalence of Diabetes in Pregnancy, Obstet Gynecol Clin N Am 34 (2007) 173–199
Kelly J. Hunt, PhD, Kelly L. Schuller, PhD Department of Biostatistics, Bioinformatics and Epidemiology, Medical University of South Carolina, 135 Cannon Street,Suite 303, Charleston, SC 29425, USA
Labor and Delivery Management for Women With Diabetes Obstet Gynecol Clin N Am 34 (2007) 323–334
J. Seth Hawkins, MD, Brian M. Casey, MD Department of Obstetrics and Gynaecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA