Blood Glucose and Pregnancy

Blood Glucose and Pregnancy

Gestational diabetes is high blood sugar (diabetes) that starts or is first diagnosed during pregnancy.

Pregnancy hormones (Both the higher levels of progesterone and cortisol) can block insulin from doing its job. When this happens, glucose levels may increase in a pregnant woman’s blood.
You are at greater risk for gestational diabetes if you:

  • Are older than 25 when you are pregnant
  • Have a family history of diabetes Gave birth to a baby that weighed more than 9 pounds or had a birth defect
  • Have sugar (glucose) in your urine when you see your doctor for a regular prenatal visi
  • Have high blood pressure
  • Have too much amniotic fluid
  • Have had an unexplained miscarriage or stillbirth
  • Were overweight before your pregnancy
Blood Glucose and Pregnancy


Usually there are no symptoms, or the symptoms are mild and not life threatening to the pregnant woman. Often, the blood sugar (glucose) level returns to normal after delivery.
Symptoms may include:

  • Blurred vision
  • Fatigue
  • Frequent infections, including those of the bladder, vagina, and skinIncreased thirst
  • Increased urination
  • Nausea and vomiting
  • Weight loss in spite of increased appetite


Gestational diabetes usually starts halfway through the pregnancy. All pregnant women should receive an oral glucose tolerance test between the 24th and 28th week of pregnancy to screen for the condition. Women who have risk factors for gestational diabetes may have this test earlier in the pregnancy.
Once you are diagnosed with gestational diabetes, you can see how well you are doing by testing your glucose level at home.


The goals of treatment are to keep blood sugar (glucose) levels within normal limits during the pregnancy, and to make sure that the growing baby is healthy.
Your health care provider should closely check both you and your baby throughout the pregnancy. Fetal monitoring to check the size and health of the fetus often includes ultrasound and nonstress tests.

  • A nonstress test is a very simple, painless test for you and your baby. A machine that hears and displays your baby’s heartbeat (electronic fetal monitor) is placed on your abdomen. When the baby moves, the baby’s heart rate normally increases 15 – 20 beats above its regular rate. Your health care provider can compare the pattern of your baby’s heartbeat to movements and find out whether the baby is doing well. The health care provider will look for increases in the baby’s normal heart rate occurring within a certain period of time.

Most women with gestational diabetes are able to control their blood sugar and avoid harm to themselves or their baby.
Pregnant women with gestational diabetes tend to have larger babies at birth. This can increase the chance of problems at the time of delivery, including:

  • Birth injury (trauma) because of the baby’s large size
  • Delivery by c-section

Your baby is more likely to have periods of low blood sugar (hypoglycemia) during the first few days of life.
Mothers with gestational diabetes have an increased risk for high blood pressure during pregnancy.
There is a slightly increased risk of the baby dying when the mother has untreated gestational diabetes. Controlling blood sugar levels reduces this risk.
High blood sugar (glucose) levels often go back to normal after delivery. However, women with gestational diabetes should be watched closely after giving birth and at regular doctor’s appointments to screen for signs of diabetes. Many women with gestational diabetes develop diabetes within 5 – 10 years after delivery. The risk may be increased in obese women.

Type 1 and Type 2 Diabetes

Pregnant women with diabetes, who are risk of having larger than normal babies, are encouraged to check their blood sugars often, namely 4-8 times a day.

Uncontrolled blood glucose can affect both the mother’s and the baby’s health.

For Mother

  • Increased chance of needing C-section
  • Preeclampsia
  • Miscarriage or stillbirth
  • Early or preterm birth

For Baby

  • Birth defects
  • Extra large baby
  • Low blood sugar in infant after birth
  • Increased chance of overweight obesity and diabetes in your child later in life

Always make sure that your blood glucose is under control and at good levels before becoming pregnant. See Sections on Type 1 and Type 2 diabetes.

Cortisol and Pregnancy

During pregnancy increased steroid hormone production is essential to meet both the maternal demand for increased estrogens and cortisol and the fetal demand for reproductive and somatic growth and development. In addition, alterations in the renin-angiotensin-aldosterone cascade are required to allow for a 50% increase in maternal blood volume without resulting in hypertension. These changes occur through a complex interaction amongst maternal and fetal endocrine systems in the placenta.

During pregnancy, maternal Corticotrophin-releasing hormone (CRH) levels increase dramatically, predominantly as a result of placental production. Placental CRH enters both the maternal and fetal circulation. Placental CRH production is stimulated by circulating glucocorticoids, which is in contrast to the negative feedback on hypothalamic production of CRH. Placental CRH entering the fetal circulation may stimulate the fetal pituitary-adrenal axis and this in turn may play a role in fetal organ maturation and also parturition.
During pregnancy, ACTH levels increase approximately twofold after the first trimester. This increase is, in part, placental in origin and may be a local paracrine effect of placental CRH production. Placental ACTH is not suppressible by glucocorticoids. The normal circadian rhythm of high morning and low evening ACTH and cortisol levels continues throughout pregnancy. The stress of labor causes ACTH levels to increase rapidly and then decrease within two days postpartum.

Cortisol levels increase twofold to threefold during pregnancy

Exogenous corticosteroids are variably affected by placental enzymatic activity and thus have different rates of placental transfer. This is important to consider when these medications are prescribed, because maternal and fetal availability will differ. As glucocorticoids like Dexamethasone increase placental CRH and placental ACTH activity, the Dexamethasone suppression test is unreliable in pregnancy

The Ratio of Maternal to Fetal distribution of Synthetic Steroids is

Prednisone 10 to 1
Hydrocortisone 6 to 1
Betamethasone 3 to 1
Dexamethasone 2 to 1

Adrenal cortex synthesizes three main androgens: androstenedione, dehydroepiandrosterone (DHEA) and DHEA sulfate. During pregnancy the levels of specific androgens change, because they are dependent on changes in both production rates and metabolic clearance. Androstenedione and total testosterone levels increase in pregnancy, whereas DHEA and free testosterone levels decrease.

During pregnancy, the pregnant woman must increase plasma volume, and also thus sodium reabsorption, without increasing blood pressure. In spite of the increase in extra cellular fluid volume, plasma renin activity levels increase fourfold between 8 and 20 weeks of gestation, after which they plateau.

Aldosterone levels in pregnancy increase fourfold by 8 weeks and continue to increase reaching a tenfold increase by term. This is in response to increased renin and angiotensin 2 levels.

Maternal glucocorticoid administration should be changed from the oral to the parenteral route at times of stress during pregnancy, such as severe pregnancy emesis, infections, or delivery. A suitable regimen is hydrocortisone sodium succinate 200 to 300mgs daily i.m or by intravenous infusion.

Women with mineral-corticoid deficiency also should receive Fludrocortisone 0.05-0.10mgs daily in addition to the glucocorticoids. Fludrocortisone usually is not necessary in secondary adrenal insufficiency, as mineralocorticoid secretion is not primarily under pituitary control. In primary adrenal insufficiency, the Fludrocortisone dosage should be decreased in pregnancy if hypertension or hypokalemia occurs. Careful monitoring of electrolyte levels is required if hyperemesis gravidarum or pre-eclampsia complicate the pregnancy.

The late-term cortisol surge seems to play a role in brain development and the maturation of the lungs of the baby. When babies are born prematurely (before the late-term cortisol surge), they are more likely to experience respiratory problems and interventricular hemorrhage (bleeding in the brain). For this reason, the National Institutes of Health has recommended that women at risk for premature delivery be given cortisol.

Some studies report that basal cortisol levels decline within a few days after childbirth. However, basal cortisol levels remain high in some postpartum women, and basal cortisol may not return to pre-pregnant levels until after eight weeks postpartum. This suggests that some postnatal mood disorders could be caused by elevated cortisol. There is also the possibility that reduced cortisol causes mood problems. When postpartum women experience a rapid withdrawal of cortisol shortly after birth, they may be at greater risk for developing depression.

Thyroid and Pregnancy

Some women have a thyroid disorder that began before pregnancy. Others develop thyroid problems for the first time during pregnancy or soon after delivery.

The demand for thyroid hormones increases in about 20 weeks of gestation and persists until term.

The fetus has two potential sources of thyroid hormones, it’s own thyroid and the thyroid of it’s mother. Human fetuses acquire the ability to synthesize thyroid hormones at 10 to 12 weeks of gestation. Current evidence from several species indicates that there is substantial transfer of maternal thyroid hormones across the placenta. Additionally, the placenta contains deiodinases that can convert T4 to T3.

Thyroid anti-bodies (TPO and TgAB) cross the placenta and may attack the fetal thyroid.

If hypothyroidism isn’t diagnosed and treated properly during pregnancy, it could lead to serious complications:

For Mother

  • Preeclampsia
  • Miscarriage
  • Stillbirth
  • Congestive Heart Failure
  • Anemia

For Baby

  • Low birth weight
  • Decreased mental abilities
  • Thyroid disorders
  • Death


See the section on Hypothyroidism.
In pregnancy testing of thyroid hormones should be done every 2 months.


See the section on Hypothyrodisim

Complications from hyperthyroidism:

  • congestive heart failure (which most likely is caused by high Reverse T3)
  • preeclampsia-a dangerous rise in blood pressure in late pregnancy
  • thyroid storm-a sudden, severe worsening of symptoms
  • miscarriage
  • premature birth
  • low birth weight


Antithyroid drugs cross the placenta in small amounts and can decrease fetal thyroid hormone production, so the lowest possible dose should be used to avoid hypothyroidism in the baby. Beta blockers (to control heart rate) and iodides can not be used because they may cause problems with your placenta, growth retardation of the fetus or an underactive fetal thyroid. Therefore these drugs are only used in extreme circumstances when the mother’s life is in danger or when thyroid surgery is required. Radioactive iodine also can not be used because the radioactive iodine may destroy the fetal thyroid as well as the mother’s thyroid gland, resulting in a hypothyroid baby. In this case, not only is the baby at risk for intellectual and physical growth retardation, but the hypothyroidism may cause severe enlargement of the baby’s thyroid gland. The gland may be so large that it interferes with normal vaginal delivery, necessitating caesarean section. Therefore, the goal for the treatment of hyperthyroid women is twofold 1) to protect the mother and 2) to protect the developing fetus.

Even if you are taking the appropriate medicine during your pregnancy to successfully treat your hyperthyroidism, your baby is still at risk for the development of hyperthyroidism called neonatal thyrotoxicosis. Even with proper medication or surgery, thyroid stimulating antibodies may remain in your bloodstream and may be passed to your newborn baby. Therefore, your baby must be tested (with a simple blood test) immediately after birth for a possible overactive thyroid gland.

In addition, anti-thyroid drugs taken by you during your pregnancy pass through the bloodstream and placenta to your baby and mask your newborn baby’s hyperthyroidism for 7 to 10 days until these medications have worn off. Careful follow-up by the baby’s pediatrician is essential.

Postpartum depression is usually due to fatigue, hormonal fluctuations and emotional changes. However, if these symptoms are prolonged, the depression may be due to thyroid disease. Thyroid illnesses may occur up to one year after delivery.

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