Pregnancy-induced Hypertension Increases Risk of Post-pregnancy Hypertension

Women with pregnancy-induced hypertension (PIH) (PIH) have a significantly higher risk of developing hypertension during their life and regular blood pressure checks, starting post-delivery, are important to prevent complications such as heart disease and strokes, according to a recent nationwide study in Denmark published in the British Medical Journal.

Hypertension Risk in Women With PIH - What Is New In Current Study

The research team feels that existing research to determine future hypertension risk in women with PIH does not clearly outline exactly when the risk of hypertension appears postpartum and how the risk changes over time. These answers would provide valuable evidence based on which recommendations for blood pressure checks and appropriate interventions post-delivery can be made. The study team set out to answer these questions in their study.

Estimating Hypertension Risk Post-delivery in PIH – The Study

For the study, the team used two cohorts, conducted among pregnant women nationwide across Denmark.

• All pregnancies, more than 20 weeks ending in live or stillbirths from 1995-2012 to estimate the cumulative risk of post-pregnancy hypertension. This study included 482972 participants.
• All women who had at least one pregnancy more than 20 weeks ending in live or stillbirths between 1978-2012 who were living in Denmark at some point during the followup from 1995-2012. This group was used for hazard ratio (relative risk) estimation of post-pregnancy hypertension and included 1025118 women.

Findings of The Study - Cumulative Incidences of Post-pregnancy Hypertension

• In the first cohort, 22,235 (4.8%) were diagnosed with hypertension in their first pregnancy, and 16 611 (3.4%) developed hypertension subsequent during follow-up.
• Women who were normotensive during first pregnancy in their 20s, 30s, or 40s had cumulative incidences of hypertension of 4.0%, 5.7%, and 11.3%, respectively, in the 10 years (decade) following delivery.
• The corresponding cumulative incidences for women whose first pregnancy was complicated by a hypertension were 13.7%, 20.3%, and 32.4%, respectively.
• A similar pattern was noted in the decade following a second pregnancy in women with two pregnancies, where either pregnancy could have been complicated by hypertensive disorder.

Relative Risk of Post-pregnancy Hypertension

• In the second cohort of 1025118 women, 59 319 (5.8%) had one or more pregnancies complicated by hypertensive disorders between 1978 and 2012; 183 423 developed hypertension during follow-up (1995-2012).
• In the first year post-delivery incidence of post-pregnancy hypertension was 12-fold to 25-fold higher in women with a hypertensive disorder of pregnancy than in women who had normal blood pressure during pregnancy
• One to five years postpartum, hypertension rates were four to 10-fold higher in women with a hypertensive disorder of pregnancy following the most recent pregnancy.
• Subsequently, the hazard ratios decreased in women with PIH, but even after 20 years their hypertension rates were twice as higher compared to women with normotensive pregnancies.

Interestingly for women aged more than 30 years into their first pregnancy, gestational hypertension was associated with an increased risk of post-delivery hypertension than preeclampsia (a more severe hypertensive disorder of pregnancy) suggesting that the pathophysiology of gestational and essential hypertension might be similar.

Sequence Of Hypertension In Women With Two Pregnancies – How It Affects Post-delivery Hypertension

• Having a hypertensive disorder of pregnancy in the first pregnancy but not in the second was associated with a doubling of the rate of post-pregnancy hypertension, compared to having normotensive pregnancies.
• The risks were even higher in women with a normotensive first pregnancy and a hypertensive disorder in the second pregnancy.
• The largest (hazard ratio range 2.6-7.8) in women with hypertensive disorders affecting both pregnancies.

Takeaway From The Study

The important takeaway from the study is that increased risk of post-delivery hypertension appears immediately after a hypertensive pregnancy.

The highest risk is in the first year, gradually decreasing but still persists even after 20 years when the risk of post-delivery hypertension is twice as much in women who have had hypertensive pregnancies than those with normal pregnancies.

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Monitoring of blood pressure in women with PIH should begin immediately postpartum and continue longterm. This would ensure early diagnosis and putting in place appropriate measures to reduce or prevent complications such as heart disease later in life.

Hypertensive Disorders of Pregnancy

Hypertensive disorders during pregnancy are common, occurring in up to 10 percent of all pregnancies, and include gestational hypertension, preeclampsia (which is a combination of high blood pressure and proteinuria), and eclampsia, which comprises seizures in women with preeclampsia. High blood pressure develops after 20 weeks gestation and becomes normal following delivery.

Women with hypertensive disorders associated with pregnancy are at increased risk of developing essential hypertension, ischemic heart disease and stroke, prompting the American Heart Association and the European Society of Cardiology to add hypertensive disorders of pregnancy as risk factors for cardiovascular disease in women

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In conclusion, women diagnosed with hypertensive disorder during pregnancy should discuss periodic checking of their blood pressure following delivery with their physicians. Further research is needed to determine whether regular followup and treatment indeed reduces or prevents future cardiovascular disease risk in these women.

References:

1. Ida Behrens, Saima Basit, Mads Melbye, Jacob A Lykke, Jan Wohlfahrt, Henning Bundgaard, Baskaran Thilaganathan, Heather A Boyd. Risk of post-pregnancy hypertension in women with a history of hypertensive disorders of pregnancy: nationwide cohort study. The British Medical Journal (2017). doi: https://doi.org/10.1136/bmj.j3078

Source-Medindia