Women who experience anxiety about their pregnancies give birth earlier on average than those who don’t, according to research published by the American Psychological Association.

On the face of it, you might think: Surely, most women, especially those having their first child, will be anxious at least some of the time about the health of the baby, the horror stories of childbirth (people just love to share) and the great unknowns of what lies ahead in a life to be shared with someone totally dependent on you.

But just as there’s a difference between having “baby blues” and full-blown post-partum depression, there’s a difference between moments of feeling anxious and debilitating anxiety.

The researchers suggest that doctors might be well advised to screen for anxiety in their pregnant patients, particularly in the first and third trimesters.

“Anxiety about a current pregnancy is a potent psychosocial state that may affect birth outcomes,” said lead study author Dr Christine Dunkel Schetter of the University of California Los Angeles.

“These days, depressive symptoms are assessed in many clinic settings around the world to prevent complications of post-partum depression for mothers and children.

“This and other studies suggest that we should also be assessing anxiety in pregnant women.”

Anxious versus anxiety

Feeling anxious is a normal response to stress, fed in large part by questions of the unknown – you’re in a situation such as starting a new job, final exams are looming or you’ve moved to a new town and hoping you’ll make friends and fit in.

Will this new aspect of life work out or will it go to the dogs?

We all have these thoughts but when they become persistent worries, they can impair your daily functioning. And that’s when probably you’ve tripped over into general anxiety disorder.

This is where you develop symptoms such as fatigue, irritability, having trouble concentrating and sleeping, and signs of panic such as sweaty palms.

Anxiety in pregnancy

Previous research has found that up to 25 per cent of pregnant women have clinically elevated anxiety symptoms and that anxiety can be a risk factor for pre-term birth, or birth before 37 weeks of pregnancy.

Those studies apparently didn’t clearly discern between general and pregnant-specific anxiety – and there was a focus on the second trimester, when pregnancy is often reported to be a more tranquil experience.

The new study – which examined data from a diverse sample of 196 pregnant women in Denver and Los Angeles – used four standardised scale measures of anxiety, three developed for pregnancy, and was designed to clarify effects of timing and anxiety type.

About half of the sample was pregnant with their first child, and more than a third of the women had no risk factors or were low risk.

The Overall Anxiety Severity and Impairment Scale (OASIS) was used to screen for clinically significant levels of anxiety.

Total scores on the OASIS measure range from 0 to 20.

About 12.8 per cent of participants scored at or above eight, “indicating clinically significant anxiety”.

Main findings

Pregnancy-related anxiety in the third trimester was most strongly associated with earlier births.

However, general anxiety in the first trimester also contributed to risk for early birth.

One possibility, according to the researchers, “is that general anxiety early in pregnancy could predispose women to be anxious later in pregnancy about such issues as medical risks, the baby, labour and delivery, and parenting”.

The results held even when adjusted for the actual medical risk of the women’s pregnancies.

“Although not all women who begin pregnancy with general anxiety symptoms will later experience pregnancy-specific anxiety,” Dr Schetter said.

“Our results suggest that women who do follow this progression are likely to be especially at risk for earlier delivery.”