Type 1 During Pregnancy

What will happen during the pregnancy?

Pre-pregnancy and the First Three Months

In the first three months, your diabetes team will help you to carefully control your blood sugar because high sugar levels at this time can increase the risk of birth defects. Together, you will strive for a normal A1c with well-regulated blood sugars.  An A1c under 7.0% is generally considered to be safe (in laboratories who have an upper limit of normal of 6.1%).  Higher A1c increases the risk of a congenital malformation and an A1c of 10% poses about a 6% risk of congenital malformation. Many of these congenital malformations are minor but some are very serious, so during the first three months your team will usually monitor how your blood sugar levels are being controlled on a weekly or biweekly basis.

During this time, it is important that your doctor or caregiver measures your how your kidneys are working and also assesses whether you have any nerve or eye damage from the diabetes.  It is recommended to see an eye specialist (opthamologist) within these first three months.

Some blood pressure tablets used to protect the kidneys, called ACE and ARBs, and cholesterol lowering tablets, called statins, are not considered safe in pregnancy. Ideally, the consumption of these tablets should be stopped pre-conception.  There are safe blood pressure tablets for pregnancy. Taking prenatal vitamins and folic acid is recommended. Talk to your physician if you have any concerns.

In order to achieve excellent blood glucose control, it is recommended that you measure your blood sugar before breakfast, lunch, supper and at bedtime as a minimum.  It is also advisable that you check some values two hours after a meal to make sure that the sugar is not rising too high.

Your diabetes team will give you advice on how best to adjust the insulin.  To obtain the target blood sugar values, most women need to take insulin at least four times a day.

The suggested target blood sugar values on your meter for pregnancy are:

Before breakfast
3.5 – 5.3 mmol.l  (63 – 95 mgs/dl)

Before meals
3.5 – 6.0 mmol/l  (63 – 108 mgs/dl)

5.0 – 7.0 mmol/l  (90 – 126 mgs/dl)

2 hours after a meal
less than 6.7 mmol/l  (121 mgs/dl)

These targets are quite strict and may be associated with some mild low blood sugar reactions, but low blood sugars do not harm the baby unless very prolonged and severe.  If the low blood sugar reactions become severe, let your caregiver/physician know so that your target values can be re-set at a higher level.

When aiming for these low blood sugar values, it is advisable that you keep something to treat a reaction in the car. If it is coming close to a snack or mealtime (a high risk time for a reaction) and you need to drive it’s advisable to check your sugar before you get behind the wheel. If you have any problem sensing low sugars you must check your glucose each time you drive. Talk to your diabetes team about safe solutions.

The second trimester

During this stage good blood sugar control helps to prevent your baby from getting too big and being at risk for low blood sugar after birth.  Your physician or health care team will monitor your A1c and kidney function regularly, once a month until they are normal, and then every one-two months. You can also talk to your team about bringing your meter with you to do a blood glucose check that can be double-checked by a laboratory.  This will ensure that your meter is reading accurately.

Owing to the increased risk of birth defects in babies of women with diabetes, an ultrasound can be done at this time to check for any malformation that may have occurred during the first three months.  This is usually arranged in conjunction with the obstetrician.  If there are abnormalities, your obstetrician will discuss these with you.

The insulin requirements will usually rise gradually during these second three months.  This is because the placenta or afterbirth is releasing hormones that circulate in your body and block the insulin that you are giving yourself.  This is perfectly normal but it does mean you will need more insulin and so you should be prepared to adjust the insulin every few days and keep adjusting it as needs be to match the insulin resistance.

The third trimester

You may need more frequent appointments in this critical stage of your pregnancy to ensure the blood sugar, blood pressure and urine protein are well monitored.  There is a very slightly increased risk of stillbirth for infants of women with diabetes and therefore if you notice any significant decrease in fetal movements, you should contact your obstetrician that same day.  Your obstetrician can arrange for a non-stress test on the labor floor.  This non-stress test only takes about a half an hour.  Many obstetricians will routinely arrange monitoring of the baby to ensure all is well.

The amount of insulin you need usually continues to increase, though it typically levels out from about thirty-six weeks onwards.  In about two-thirds of women it may drop by as much as 10-20%.  If it drops dramatically (more than 20%) over the course of a few days, it may be a warning sign that the placenta is not working as well as it should be. In this scenario, your obstetrician will monitor your baby more carefully and may admit you to the hospital for a few days.


Depending on the duration of the diabetes and any other problems, your obstetrician will most likely suggest a normal vaginal delivery.  However, if any problems arise, you should talk to your doctor about a C-section.  This is because infants of diabetic mothers are considered high risk.

For the delivery, insulin and glucose are administered intravenously in most centers.  Blood sugar levels will usually be checked every hour so that the insulin can be regulated accordingly.  If you know you are going to be induced on a certain morning, you should take less long-acting insulin the night before.

After delivery of the baby and afterbirth the insulin will be stopped and your blood sugar will be checked regularly.  The insulin is restarted once the glucose rises over 10 mmol/l  (180 mgs/dl). If you’ve had a C-section and are unable to eat for a couple of days, the insulin will be given intravenously. If you’re eating normally, you will be given the insulin you were given pre-pregnancy but at a dose at least 10%  lower until your body readjusts .

Talk to your physician about scheduling a check-up 6 weeks after the baby is born.