Blood Pressure, Antihypertensive Treatment and Preeclampsia in Pregnant Wom-en With Pre-existing Diabetes

Aim: First, to investigate the prevalence of a) confirmed hypertension, b) white coat hypertension and c) normal blood pressure in pregnant women with pre-existing diabetes. Second, to explore the prevalence of preeclampsia and preterm delivery in women with pre-existing diabetes with a) confirmed hypertension, b) white coat hypertension and c) normal blood pressure before entering the third trimester of pregnancy. Third, to explore the influence of lifestyle, gestational weight gain and mental well-being on confirmed hypertension and preeclampsia in pregnant women with diabetes.The recruitment period was in 2018 extended to 2020 to perform the following studies: First whether home BP in early pregnancy is superior to office BP to predict preeclampsia. Second to evaluate the prevalence of preeclampsia after initiation of a new treatment strategy including prophylactic aspirin and, in case of insufficiency, vitamin D supplementation.

Design: A prospective multicentre observational study where approximately 400 pregnant women with pre-existing diabetes are offered measurements of office blood pressure (BP) and home BP for three days three times during pregnancy as well as when the routinely measured office BP exceeds 135/85 mmHg. The prevalence of confirmed hypertension (office BP \>135/85 mmHg and home BP \>130/80 mmHg) and white coat hypertension (office BP \>135/85 mmHg but home BP ≤130/80 mmHg) will be determined. Women with confirmed hypertension are offered antihypertensive treatment mainly with methyldopa. In women with a) confirmed hypertension, b) white coat hypertension, and c) normal blood pressure before entering third trimester of pregnancy, the prevalence of preeclampsia and preterm delivery will be evaluated. Possible side effects of antihypertensive treatment including impaired fetal haemodynamics and lower infant birth weight will be recorded. The women will complete food diaries and questionnaires on lifestyle and mental health three times in pregnancy in order to evaluate the influence of these parameters on hypertension and preeclampsia.

Design: Home blood pressure and office blood pressure as predictors of preeclampsia will be evaluated in the total cohort. From February 2018, the routine care includes treatment with prophylactic aspirin in all women with pre-existing diabetes and screening for vitamin D insufficiency, treated with vitamin D depending on the severity of the insufficiency. The prevalence of preeclampsia after initiation of the new treatment strategy will be evaluated. The women included from 2016-2018, where aspirin was only initiated if other risk factors to preeclampsia apart from diabetes were present, will be used for comparison.

Eligibility Criteria:
Inclusion Criteria:

Inclusion criteria for pregnant women with diabetes:

* Women with pre-existing diabetes, older than 18 years and referred to The Center for Pregnant Women with Diabetes, Rigshospitalet, or the Centre for Diabetes and Pregnancy, Odense University Hospital, with a live singleton or twin pregnancy before 20 weeks during the inclusion period.
* Women with diabetes diagnosed in pregnancy before 20 weeks (HbA1c ≥48 mmol/mol) may also be included as having type 2 diabetes.
* Sufficient Danish language skills to read and understand the patient information sheet and to converse.

Inclusion criteria for pregnant healthy women without diabetes:

* Women above 18 years of age, with a live singleton pregnancy, referred to a nuchal translucency scan at 11-14 weeks at The Department of Obstetrics, Rigshospitalet.
* Sufficient Danish language skills to read and understand the patient information sheet and to converse.

Exclusion Criteria:

Exclusion criteria for both study groups:

• Women diagnosed with severe diseases that could possibly bias BP measurements or pregnancy outcome. This is judged by the principal investigators.