A new study finds that the antibiotic nitrofurantoin, marketed under numerous brand names, is safe for pregnant women. (Photo: Colourbox)
A new study finds that the antibiotic nitrofurantoin, marketed under numerous brand names, is safe for pregnant women. (Photo: Colourbox)

Key antibiotic green-lighted for pregnant women

A study of over 180,000 pregnant Norwegian women showed no increase in birth defects from a common antibiotic used for treating urinary infections.

Published

About 10 percent of women in Norway contract urinary infections during pregnancies. If untreated, these lead to an increased risk of an inflammation of the renal pelvis, pyelitis, or worse − a premature birth.

“This is why researchers in this field widely concur that urinary tract infections among pregnant women should be treated with antibiotics. But questions have arisen as to whether a certain common antibiotic is safe during pregnancies. Norwegian data now indicates that the antibiotic nitrofurantoin is not harmful to the foetus,” says Hedvig Nordeng.

She is a professor of pharmacology at the University of Oslo’s School of Pharmacy. She led a population cohort study of 180,000 Norwegian women who were pregnant in the years 2004 to 2007.

No link found

Nearly 5,800 – about 3 percent – of the 180,000 expectant women purchased this prescription medicine nitrofurantoin at pharmacies during the years 2004 to 2007.

Hedvig Marie Egeland is a professor at the University of Oslo (UiO)’s School of Pharmacy. (Photo: UiO)
Hedvig Marie Egeland is a professor at the University of Oslo (UiO)’s School of Pharmacy. (Photo: UiO)

The medical researchers were particularly keen on investigating the 1,334 women − 0,7 percent −  who were dispensed the drug during the first trimester of their pregnancies. This is the main time of basic development of all vital organs and the risk of injury to the foetus is greatest.

The women who used nitrofurantoin were no more prone to give birth to babies with defects than those who had not been given the drug. Contrarily, on average they were less at risk.

“The difference was statistically negligible. What’s essential is that we can now show that no additional children are born with defects after the use of this major antibacterial medication,” says Nordeng.

The professor of pharmacology knows that some physicians have had concerns about prescribing nitrofurantoin to pregenant women with urinary tract infections. She’s now interested in spreading word that research shows it is generally safe to use – also in the first trimester. 

Common remedy at the pharmacy

Nitrofurantoin has been on sale for a long time.

This antibiotic was launched in the early 1950s, about a decade after penicillin, accidentally discovered by the British physician Alexander Fleming in 1928, was initially mass produced.

“This has been a great medication for many years. Now it is used solely for women with urinary tract infections, for which it’s very effective. It would be a shame if it couldn’t be used in connection with pregnancies.”

Hedvig Nordeng adds that bacterial resistance has not been linked much to the use of nitrofurantoin.

Complete the entire cure!

The pharmacology professor stresses that pregnant women who are prescribed antibiotics by a doctor should complete any cures they have started.

“Don’t stop halfway! We encourage doctors and pharmacists to be very insistant about this with regard to pregnant patients. We know that some women get worried when they hear others warn them about the use of antibiotics when pregnant. There’s a risk that some of these women quit taking the medicine too soon. Others might stop taking it prematurely because they feel they’ve been cured.”

“This increases the risk of developing a resistance to the drug, and urinary tract infections can become tougher to treat. This can affect the mother and the child,” explains Nordeng.

The doctor’s advice

When pregnant women see their doctors for urinary tract infections they will probably find that the physicians initially prescribe a treatment with penicillin medications such as Selexid or Penomax. The professor confirms that this is the right procedure.

Nitrofurantoin (Furadantin) should generally be the secondary option for treatment of urinary tract infections during pregnancy. It can also be used by women who are allergic to penicillin, or if penicillin medications are ineffective. 

Professor Morten Lindbæk of the University of Oslo heads the Antibiotic Centre for Primary Care, and thus has a key responsibility for guidelines to Norwegian physicians about the use of antibiotics.

New guidelines are being published in April 2013.  Lindbæk confirms that these will include advice on the use of nitrofurantoin during pregnancies.

“We are very concerned about having proper antibiotic treatment procedures in Norway, especially for pregnant women. Two individuals are being treated simultaneously. The knowledge acquired through this research project enables doctors to give sound advice to pregnant patients.”

“As a rule, antibiotics should be used as little as possible. This helps ensure that antibiotics continue to be a fantastic remedy. We are always concerned about liberal antibiotics policies leaving us with more criticial resistance problems, as we see happening further south in Europe,” says Lindbæk.

Hedvig Nordeng say that researchers have a minor reservation regarding use of nitrofurantoin in the final 30 days of pregnancy. They find a slightly higher risk of jaundice among the new-borns of women who have been dispensed the drug (10.8 prosent) as compared to all new-borns (8.1 percent).

The study involved collaboration between the University of Oslo, the Norwegian Institute of Public Health and the Hospital for Sick Children in Toronto, Canada.

Unique Norwegian registry

In recent years the extensive health data available about the Norwegian population has opened new opportunities for researchers.

In this study the scientists combined data from the Norwegian Prescription Database and the Medical Birth Registry of Norway. 

This gave them a list of pregnant women who filled prescriptions for the medication Furadantin (which contains the antibiotic nitrofurantoin) at Norwegian pharmacies. They linked these to data on women who gave birth to infants with defects.

“The ingenious thing here is our national insurance (social security) number system,” says Nordeng.

“Not every country has such numbers, which are used across the board throughout society. The number enables us to link data from our large health databases. We are now witnessing the big advantages these provide.”

“When I’m abroad and present the results we’ve found, colleagues in the Nordic countries say we are fabulously lucky to have health registers which comprise the entire population and which can also be interlinked. This can put us in the vanguard of such research,” claims Nordeng.

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Read the Norwegian version of this article at forskning.no

Translated by: Glenn Ostling

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