Mothers of premature babies ‘more than TWICE as likely to develop high blood pressure’

Mothers of premature babies are more than twice as likely to develop high blood pressure, a large study has claimed.

Experts say the findings mean that doctors should now consider preterm labor as a “lifetime” risk factor for hypertension in women and subsequent cardiovascular diseases such as heart attacks and strokes.

The study followed more than 2 million Swedish women for nearly 45 years, allowing researchers to examine both the immediate and long-term risk of hypertension after birth.

The results showed that after ten years, women who gave birth too early were 67 percent more likely to have high blood pressure.

A study of more than 2 million pregnant women in Sweden found that women with preterm birth had a greater risk of developing high blood pressure in subsequent years. As this chart shows, the risk was higher for the women who delivered extremely preterm babies, who were born between 22 and 27 weeks. The risk of high blood pressure was also highest in the 10 years after birth, but was still present 40 years after birth. High blood pressure is a major risk factor for heart disease

Preterm births account for about 10 percent of all births in the UK and US.  Researchers say the new findings should prompt doctors to consider women's reproductive histories when assessing their risk of heart disease

Preterm births account for about 10 percent of all births in the UK and US. Researchers say the new findings should prompt doctors to consider women’s reproductive histories when assessing their risk of heart disease

Mothers’ risk of high blood pressure within 10 years of preterm birth

General: 67 percent

Extremely premature (22-27 weeks):

123 percent

Moderate Premature Birth (28-33 Weeks):

85 percent

Late Premature (34-36 weeks):

55 percent

Early term (37-38 weeks):

26 percent

All figures compared to a full-term delivery (between 39-41 weeks)

About one in ten births in the UK and the US is premature, which is considered to be before the 37th week of pregnancy.

The study found that the earlier they gave birth, the risk of developing hypertension was greater for women.

Mothers who gave birth as early as 22 weeks – which is 14 days before the UK abortion threshold – were more than twice as likely to develop high blood pressure.

But the risk was only 26 percent for women who gave birth at just over 37 or 38 weeks.

The groups were all compared to women carrying their babies to full term, between 39 and 41 weeks.

In addition, women who gave birth late, at 42 weeks, had a 14 percent lower risk of developing hypertension.

The researchers, led by Dr. Casey Crump of the Icahn School of Medicine, also found that an increased risk of hypertension persisted for more than 40 years.

They calculated that each additional week of pregnancy, after the 22nd week, resulted in an average 3 percent lower risk of hypertension.

Scientists are still not clear why women with premature babies are more prone to hypertension.

Mothers’ risk of high blood pressure within 43 years of preterm birth

General: 25 percent

Extremely premature (22-27 weeks):

42 percent

Moderate Premature Birth (28-33 Weeks):

33 percent

Late Premature (34-36 weeks):

21 percent

Early term (37-38 weeks):

11 percent

All figures compared to a full-term delivery (between 39-41 weeks)

However, recent studies have shown that preterm labor can cause inflammation of a thin membrane that lines the heart and blood vessels, called the endothelium.

Inflammation of the endothelium may be a contributing factor to the development of hypertension and cardiovascular disease.

Data from just under 2.2 million women who gave birth in Sweden between 1970 and 2015 were used in the study, which was published in JAMA Cardiology.

Of these women, just over 350,000 developed hypertension, 16 percent of the total.

The study measured only women who gave birth to only one child at a time. WHY

dr. Crump said the findings should change the way medics assess heart disease risk in women.

“Cardiovascular risk assessment in women should routinely include reproductive history that includes preterm birth and other adverse pregnancy outcomes,” he said.

“A history of preterm birth can help identify women at high risk for hypertension and cardiovascular disease, possibly long before the onset of these conditions.”

dr. Crump added that one intervention for preterm mothers at high risk of hypertension could be blood pressure monitoring through wearable technology.

Heart disease is the biggest killer of women in the UK, with 24,000 women dying from a condition each year. It is also the leading cause of death for women in the US, killing 300,000 women each year

The researchers were confident in their findings, as they were responsible for other factors that could cause hypertension.

They were able to rule out genetics and lifestyle factors by analyzing siblings of the women in the study.

However, they acknowledged other limitations, such as the lack of ability to verify the accuracy of hypertension diagnoses the women had received through the Swedish medical system due to a lack of clinical data.

There are also some limitations based on technical changes in gestational age reporting and various cutoffs for hypertension diagnoses between the 1970s/80s and the mid-2000s, although these were considered minor limitations by the authors.

This study is the latest by the same authors on the health risks to women of preterm birth.

Last August, the authors found, using the same dataset, that women who have a premature baby are much more likely to die young than other mothers.

EXPLAINED: PREMATURE BIRTH AND THE RISKS FOR BABIES

About 10 percent of all pregnancies worldwide result in preterm labor – defined as delivery before 37 weeks.

When this happens, not all of the baby’s organs, including the heart and lungs, will have developed. They may also be underweight and smaller.

Tommy’s, a UK-based charity, says this could mean premature babies “are not ready for life outside the womb.”

Premature birth is the leading cause of neonatal death in the US and UK, according to figures.

Premature babies account for around 1,500 deaths a year in the UK. In the US, preterm birth and its complications are responsible for 17 percent of infant deaths.

Premature babies are often taken to neonatal intensive care units, where they are cared for around the clock.

What are the chances of survival?

  • Less than 22 weeks is almost zero chance of survival
  • 22 weeks is about 10%
  • 24 weeks is about 60%
  • 27 weeks is about 89%
  • 31 weeks is about 95%
  • 34 weeks equals a full-term baby

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