Diabetes and pregnancy

For pregnant women with diabetes, some particular challenges exist for both mother and fetus. If the pregnant woman has diabetes as a pre-existing disorder, it can cause early labor, birth defects, and larger than average infants. Therefore, experts advise diabetics to maintain blood sugar level close to normal range about 3 months before planning for pregnancy.^[1]

When type 1 diabetes mellitus or type 2 diabetes mellitus is pre-existing, planning in advance is emphasized if one wants to become pregnant, and stringent blood glucose control is needed before getting pregnant.^[1]

Physiology

Pre-gestational diabetes can be classified as Type 1 or Type 2 depending on the physiological mechanism. Type 1 diabetes mellitus is an autoimmune disorder leading to destruction of insulin-producing cell in the pancreas; type 2 diabetes mellitus is associated with obesity and results from a combination of insulin resistance and insufficient insulin production. Upon becoming pregnant, the placenta produces human placental lactogen (HPL), a hormone with counter-regulatory actions leading to increased blood glucose levels.^[2] In combination with pre-existing diabetes, these maternal physiological changes can lead to dangerously high blood glucose levels. This is significant because the consequences of poor glycemic control are more severe during pregnancy compared to non-pregnant states.

Risks for the fetus

The negative effects of pregestational diabetes are due to high blood sugar and insulin levels primarily during the first trimester of pregnancy (in contrast to gestational diabetes, which can lead to fetal complications during the second and third trimester). Since this period is when many of the major internal structures and organs of the fetus is decided, pre-existing diabetes can lead to congenital abnormalities. These include abnormal development of the heart and the central nervous system (brain and spinal cord). Strong correlations have been reported between diabetes and sacral agenesis, holoprosencephaly, and longitudinal limb deficiency.^[3] With regards to the heart, increased likelihood of truncus arteriosus, atrioventricular septal defect, and single ventricle complex has been found.^[4] It is important to note that these complications are generally rare and can be averted with tight blood sugar control. Mild neurological and cognitive deficits in offspring — including increased symptoms of ADHD, impaired fine and gross motor skills, and impaired explicit memory performance — have been linked to pregestational type 1 diabetes and gestational diabetes.^[5]^[6]^[7]

Pre-existing diabetes can also lead to complications in the neonate after birth, including neonatal jaundice, hypoglycemia, and macrosomia. Pregestational diabetes does not, however, increase the likelihood of diseases due to chromosomal alterations (e.g., Down Syndrome). Furthermore, miscarriages are also increased due to abnormal development in the early stages of pregnancy.^[8]

Furthermore, when blood glucose is not controlled, shortly after birth, the infant's lungs may be under developed and can cause respiratory problems.^[9] Hypoglycemia can occur after birth if the mother's blood sugar was high close to the time of delivery, which causes the baby to produces extra insulin of its own. A hyperglycemic maternal environment has also been associated with neonates that are at greater risk for development of negative health outcomes such as future obesity, insulin resistance, type 2 diabetes mellitus, and metabolic syndrome.^[10]

Diabetes pregnancy management

Blood glucose levels in pregnant women should be regulated as strictly as possible. During the first weeks of pregnancy less insulin treatment is required due to tight blood sugar control as well as the extra glucose needed for the growing fetus.^[11] At this time basal and bolus insulin may need to be reduced to prevent hypoglycemia. Frequent testing of blood sugar levels is recommended to maintain control. As the fetus grows and weight is gained throughout the pregnancy, the body produces more hormones which may cause insulin resistance and the need for more insulin.^[11] At this time it is important for blood sugar levels to remain in range as the baby will produce more of its own insulin to cover its mother's higher blood sugar level which can cause fetal macrosomia.^[12] During delivery, which is equivalent to exercise, insulin needs to be reduced again or hyperglycemia can occur. After the baby is delivered and the days following, there are no more hormones from the placenta which demanded more insulin, therefore insulin demand is decreased and gradually returns to normal requirements.^[9]

Diabetes mellitus may be effectively managed by appropriate meal planning, increased physical activity and properly-instituted insulin treatment. Some tips for controlling diabetes in pregnancy include:

Cut down sweets, eats three small meals and one to three snacks a day, maintain proper mealtimes, and include balanced fiber intake in the form of fruits, vegetables and whole-grains.
Increased physical activity - walking, swimming/aquaerobics, etc.
Monitor blood sugar level frequently, doctors may ask to check the blood glucose more often than usual.
The blood sugar level should be below 95 mg/dL (5.3 mmol/L) on awakening, below 140 mg/dL (7.8 mmol/L) one hour after a meal and below 120 mg/dL (6.7 mmol/L) two hours after a meal.
Each time when checking the blood sugar level, keep a proper record of the results and present to the health care team for evaluation and modification of the treatment. If blood sugar levels are above targets, a perinatal diabetes management team may suggest ways to achieve targets.
Many may need extra insulin during pregnancy to reach their blood sugar target. Insulin is not harmful for the baby.^[13]

The National Institute of Health and Care Excellence now recommends closed-loop insulin systems as an option for all women with type 1 diabetes who are pregnant or planning pregnancy.^[14]^[15]^[16]

Breastfeeding

In general, breast feeding is good for the child even with a mother with diabetes mellitus. In fact, the child's risk for developing type 2 diabetes mellitus later in life may be lower if the baby was breast-fed. Breast feeding also helps the child maintain a healthy body weight during infancy. However, the breastmilk of mothers with diabetes has been demonstrated to have a different composition than that of non-diabetic mothers, containing elevated levels of glucose and insulin and decreased polyunsaturated fatty acids.^[17] Although benefits of breast-feeding for the children of mothers with diabetes have been documented, ingestion of diabetic breast milk has also been linked to delayed language development on a dose-dependent basis.^[17]

In some cases, pregnant women with diabetes may be encouraged to express and store their colostrum during pregnancy, in case their blood sugar is too low for feeding the baby breast milk after birth.^[18] There is no evidence on the safety or potential benefits when pregnant women with diabetes express and store breast milk prior to the baby's birth.^[18]

Classification

The White classification, named after Priscilla White^[19] who pioneered research on the effect of diabetes types on perinatal outcome, is widely used to assess maternal and fetal risk. It distinguishes between gestational diabetes (type A) and diabetes that existed before pregnancy (pregestational diabetes). These two groups are further subdivided according to their associated risks and management.^[20]

There are 2 classes of gestational diabetes (diabetes which began during pregnancy):

Class A₁: gestational diabetes; diet controlled
Class A₂: gestational diabetes; medication controlled

The second group of diabetes which existed before pregnancy can be split up into these classes:

Class B: onset at age 20 or older or with duration of less than 10 years
Class C: onset at age 10-19 or duration of 10–19 years
Class D: onset before age 10 or duration greater than 20 years
Class E: overt diabetes mellitus with calcified pelvic vessels
Class F: diabetic nephropathy
Class R: proliferative retinopathy
Class RF: retinopathy and nephropathy
Class H: ischemic heart disease
Class T: prior kidney transplant

An early age of onset or long-standing disease comes with greater risks, hence the first three subtypes.

Footnotes

^ ^a ^b "Pregnancy if You Have Diabetes | NIDDK". National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved 2020-10-29.
^ Barbour, Linda A.; McCurdy, Carrie E.; Hernandez, Teri L.; Kirwan, John P.; Catalano, Patrick M.; Friedman, Jacob E. (2007-07-01). "Cellular Mechanisms for Insulin Resistance in Normal Pregnancy and Gestational Diabetes". Diabetes Care. 30 (Supplement 2): S112 – S119. doi:10.2337/dc07-s202. ISSN 0149-5992. PMID 17596458.
^ "Home - Eastern Virginia Medical School (EVMS), Norfolk, Hampton Roads". www.evms.edu. Retrieved 2021-09-10.
^ Tinker, Sarah C.; Gilboa, Suzanne M.; Moore, Cynthia A.; Waller, D. Kim; Simeone, Regina M.; Kim, Shin Y.; Jamieson, Denise J.; Botto, Lorenzo D.; Reefhuis, Jennita (February 2020). "Specific birth defects in pregnancies of women with diabetes: National Birth Defects Prevention Study, 1997–2011". American Journal of Obstetrics and Gynecology. 222 (2): 176.e1–176.e11. doi:10.1016/j.ajog.2019.08.028. PMC 7186569. PMID 31454511.
^ Nomura Y, Marks DJ, Grossman B, Yoon M, Loudon H, Stone J, Halperin JM (January 2012). "Exposure to Gestational Diabetes Mellitus and Low Socioeconomic Status: Effects on Neurocognitive Development and Risk of Attention-Deficit/Hyperactivity Disorder in Offspring". Archives of Pediatrics & Adolescent Medicine. 166 (4): 337–43. doi:10.1001/archpediatrics.2011.784. PMC 5959273. PMID 22213602.
^ Ornoy A, Ratzon N, Greenbaum C, Wolf A, Dulitzky M (2001). "School-age children born to diabetic mothers and to mothers with gestational diabetes exhibit a high rate of inattention and fine and gross motor impairment". Journal of Pediatric Endocrinology & Metabolism. 14 Suppl 1: 681–9. doi:10.1515/jpem.2001.14.s1.681. PMID 11393563. S2CID 11884127.
^ DeBoer T, Wewerka S, Bauer PJ, Georgieff MK, Nelson CA (August 2005). "Explicit memory performance in infants of diabetic mothers at 1 year of age". Developmental Medicine and Child Neurology. 47 (8): 525–31. doi:10.1017/s0012162205001039. PMC 2829746. PMID 16108452.
^ "First Trimester complications in pregnancy with diabetes". September 2016. Archived from the original on 2018-11-25. Retrieved 2018-11-06.
^ ^a ^b Walsh, John (2006). Pumping Insulin. San Diego, California: Torrey Pines Press. p. 288. ISBN 978-1-884804-86-1.
^ Calkins, Kara; Sherin Devaskar (2011). "Fetal Origins of Adult Disease". Curr Probl Pediatr Adolesc Health Care. 41 (6): 158–176. doi:10.1016/j.cppeds.2011.01.001. PMC 4608552. PMID 21684471.
^ ^a ^b Scheiner, Gary (2004). Think like a Pancreas. Da Capo Press. pp. 173. ISBN 978-156924-436-4.
^ "Infant of Diabetic Mother". Children's Hospital of Philadelphia. 2014-08-24.
^ "Prenatal Care | ADA". www.diabetes.org. Retrieved 2020-10-29.
^ "Overview | Diabetes in pregnancy: management from preconception to the postnatal period | Guidance | NICE". www.nice.org.uk. 2015-02-25. Retrieved 2024-01-31.
^ Lee, Tara T.M.; Collett, Corinne; Bergford, Simon; Hartnell, Sara; Scott, Eleanor M.; Lindsay, Robert S.; Hunt, Katharine F.; McCance, David R.; Barnard-Kelly, Katharine; Rankin, David; Lawton, Julia; Reynolds, Rebecca M.; Flanagan, Emma; Hammond, Matthew; Shepstone, Lee (2023-10-26). "Automated Insulin Delivery in Women with Pregnancy Complicated by Type 1 Diabetes". New England Journal of Medicine. 389 (17): 1566–1578. doi:10.1056/NEJMoa2303911. ISSN 0028-4793. Archived from the original on 19 October 2023.
^ "Closed-loop insulin systems are effective for pregnant women with type 1 diabetes". NIHR Evidence. 16 January 2024.
^ ^a ^b Rodekamp E, Harder T, Kohlhoff R, Dudenhausen JW, Plagemann A (2006). "Impact of breast-feeding on psychomotor and neuropsychological development in children of diabetic mothers: role of the late neonatal period". Journal of Perinatal Medicine. 34 (6): 490–6. doi:10.1515/JPM.2006.095. PMID 17140300. S2CID 26423226.
^ ^a ^b East, Christine E.; Dolan, Willie J.; Forster, Della A. (2014-07-30). "Antenatal breast milk expression by women with diabetes for improving infant outcomes" (PDF). The Cochrane Database of Systematic Reviews. 2014 (7): CD010408. doi:10.1002/14651858.CD010408.pub2. ISSN 1469-493X. PMC 9939873. PMID 25074749.
^ White P (November 1949). "Pregnancy complicating diabetes". Am. J. Med. 7 (5): 609–16. doi:10.1016/0002-9343(49)90382-4. PMID 15396063.
^ Gabbe S.G., Niebyl J.R., Simpson J.L. OBSTETRICS: Normal and Problem Pregnancies. Fourth edition. Churchill Livingstone, New York, 2002. ISBN 0-443-06572-1