The ups and downs of married life take their toll on dads’ hearts, a new study found.

The roller-coaster relationship between spouses causes blood pressure, bad cholesterol and weight to rise and fall in men compared to those in stable relationships.

When things are bad and the relationship is deteriorating, men’s blood pressure soars.

But when they got along better with their wives, men saw their bad cholesterol and weight drop and generally saw cholesterol and blood pressure improve.

Studies have shown that marriage tends to be good for a man’s health and life expectancy.

But it has not been clear whether this observed link was influenced by the health of people entering into marriage or the protective effects of the marriage itself.

Most studies looked at the quality of a marriage and the risk of cardiovascular disease (CVD) at a single point in time, rather than the potential impact of changes over time.

So researchers from the Universities of Bristol and Glasgow tracked changes in cardiovascular risk factors for 620 married fathers taking part in the Avon Longitudinal Study of Parents and Children (ALSPAC), which began in 1991.

The dads completed a questionnaire to assess the quality of their marital relationship when their child was nearly 3 and again when their child was 9.

Relationship quality was defined as consistently good, consistently bad, improving, or deteriorating.

The dad’s blood pressure, resting heart rate, weight (BMI), blood fat profile, and fasting glucose levels were then measured between 2011 and 2013 when their child was nearly 19.

This was to allow time for changes in cardiovascular risk factors to occur after any corresponding changes in relationship quality.

Research fellow Dr. Ian Bennett-Britton of the School of Social and Community Medicine, University of Bristol, said: “Married men have been shown to have reduced CVD mortality and morbidity, though the reasons for this remain unclear.

“This is the first study to assess the association between repeated measures of marital relationship quality and a broad range of CVD risk factors over two decades.

“Overall, among married men there were only very modest benefits in terms of CVD risk factors, if at all, when comparing men in persistently good or bad relationships.

“However, changes in marital quality had positive or negative effects on lipids and BP, as we had predicted a priori, and a modest degree of this may have been mediated through changes in adiposity.”

After taking account of potentially influential factors, such as age, education, height, and income, improving relationships were associated with lower (0.25 mmol/l) levels of low-density lipoprotein (“bad” cholesterol) and relatively lower weight (around 1 BMI unit lower) when compared with consistently good relationships.

And they were more weakly associated with improved total cholesterol (0.24 mmol/l lower) and improved diastolic blood pressure (2.24 mm Hg lower).

Deteriorating relationships, on the other hand, were associated with worsening diastolic blood pressure (2.74 mm Hg higher).

Bennett-Britton added: “Traditionally, beneficial effects of marital status were thought to be mediated by either health selection, confounding by socioeconomic status, or psychosocial mechanisms.

“The latter argument has been used to support the observation that men appear to gain more benefit than women, as women have larger social networks and are less dependent on their partner than men.

“We used a question on marital status as a marker of a long-term partnership, though it is unclear whether the same effects would have been seen with cohabitation or whether marriage has additional effects.

“This is important as marriage and cohabitation trends in developed countries have changed substantially in the last 50 years, with cohabiting in the UK doubling between 1996 and 2012.

“Changes in the quality of a marital relationship appear to predict CVD risk, though consistently good or poor relationship groups were not very different.

“At this stage, it is unclear whether these patterns will be reflected in actual rates of disease onset as the cohort is still relatively young.

“Assuming a causal association, then marriage counseling for couples with deteriorating relationships may have added benefits in terms of physical health over and above psychological well-being, though in some cases ending the relationship may be the best outcome.”

The study was published in the BMJ’s Journal of Epidemiology & Community Health.