Infant and adult weight interact to determine urinary incontinence risk

By Joanna Lyford, Senior medwireNews Reporter

A woman’s weight at birth together with her weight in adulthood influence the risk of incident urinary incontinence, results of a nationwide twin study suggest.

The Swedish research, published in International Urogynecology Journal, found that the combination of low birthweight and being overweight as an adult was associated with a near-doubling in the risk for urinary incontinence and stress urinary incontinence.

“[O]other studies are needed to confirm the association, which in the future may form an essential part of individual preventive counseling”, write Giorgio Tettamanti (Karolinska Institutet, Stockholm) and colleagues.

The researchers analysed information on 14,094 female participants in the Swedish Twin Registry who were born between 1959 and 1985 and re-evaluated in 2005. In all, 9.3% of the women were born small for gestational age (<10th percentile) and 42.7% had a low birthweight (<2500 g).

The prevalence of urinary incontinence at the point of re-assessment did not differ according to birthweight or whether the women were born small for their gestational age. This was true for urinary incontinence overall and for specific incontinence subtypes (stress, urge, mixed).

However, women with low birthweight who were overweight or obese in adulthood had the highest prevalence of overall and stress urinary incontinence. These conditions were also highly prevalent among women born after 42 weeks’ gestation.

In analyses that adjusted for a range of confounders, the risk of urinary incontinence was significantly increased in women who had a low birthweight and were overweight as adults (adjusted odds ratio [aOR]=1.84). These women also had a significantly increased risk of stress urinary incontinence (aOR=1.83).

Tettamanti and colleagues note that, according to the developmental origins of adult disease theory, intrauterine growth restriction may alter the programmed development of metabolic and endocrine pathways and systems.

Also, studies have shown that maternal nutritional restriction and low birthweight affect the number and composition of skeletal muscle fibres and muscle strength in the offspring.

As a consequence, women with impaired muscle development caused by intrauterine growth restriction may have weaker pelvic floor and detrusor muscles and carry a higher risk of lower urinary tract dysfunction. “Such a predisposition could be exacerbated by environmental factors later in life, resulting in urinary incontinence”, they propose.

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