(CNN) Selective serotonin reuptake inhibitors, known as SSRIs, are the most common type of antidepressants prescribed to pregnant women. Yet a new study indicates that when taken during pregnancy, the drugs are associated with a higher risk of language disorders, including dyslexia, in offspring.

The children of women who took SSRIs while pregnant have a 37% greater risk of speech or language disorders compared with the children of depressed but unmedicated mothers, the researchers say.

In practical terms, if a depressed mother did not take antidepressants, her child's risk of being diagnosed with a speech or language disorder would be about 1%, but if she took an SSRI, it would increase to 1.37%, explained Dr. Alan Brown, lead author of the study and a professor of psychiatry and epidemiology at Columbia University Medical Center.

"When you have relative risks that are 1.37, they're considered to be low. But because so many people are exposed -- 6% to 10% of mothers are exposed (to antidepressants) throughout the world -- it's increasing the public health burden," Brown said, explaining that this burden amounts to more expenses.

"I don't think individuals have to worry about this, but I do think at the population level, it makes a very big difference," added Brown.

Comparing children over time

For the study, published in the journal JAMA Psychiatry on Wednesday, Brown and his colleagues examined the national medical registries of Finland. The team waded through records from 845,345 single live births between 1996 and 2010 and categorized mothers into three groups.

The first "exposure" group included 15,596 mothers who purchased SSRIs once or more before or during pregnancy. A second group consisted of 9,537 mothers who had been diagnosed with depression or another psychiatric disorder but did not purchase antidepressants during pregnancy. The third group included 31,207 mothers who had never been diagnosed with depression and never purchased antidepressants.

Brown explained that he and his colleagues used the purchase of antidepressants to represent antidepressant use. When a woman refilled her prescription, it seemed likely she had been taking the pills and wanted to continue doing so.

Using data from the registries, the researchers discovered an increased risk of speech/language disorders diagnosed among children of women who used SSRIs during pregnancy and the children of women with depression who did not take an SSRI, compared with the children of women who were not depressed (or medicated).

However, comparing children born to the two groups of depressed women, Brown and his colleagues discovered an even higher rate of speech/language disorders among the children of women who purchased SSRIs at least twice during pregnancy.

Lifetime effects

"These disorders are quite prevalent in the population. They cause significant impairment," Brown said.

Dyslexia, articulation disorders and other diagnosed language disorders can have a "potentially big effect on school function and later life function," he added. "It's a significant public health issue: A lot of therapies, speech language therapies, a lot of funds get invested. It's a large burden to society and also to individuals."

According to Anick Bérard, a pharmacy professor at the University of Montreal who specializes in pharmaceutical safety during pregnancy, "the study's findings are in line with what we know about SSRI exposure in-utero." She was not involved in the new study.

That said, she noted that a possible flaw of the study is that the data come from a large administrative database; since language impairments are difficult to assess in such databases, it is possible that not all children suffering a language disorder were accounted for. Some undiagnosed cases associated with the use of antidepressants during pregnancy may exist.

Crossing the placenta

SSRIs include Prozac (fluoxetine), Celexa (citalopram), Paxil (paroxetine), Zoloft (sertraline) and Lexapro (escitalopram). Though they are known to cross the placenta and enter the blood stream of a developing baby, doctors do prescribe them to depressed women during pregnancy.

One 2011 study of US mothers found that 4.5% reported using an antidepressant within the period of three months before pregnancy through to the birth of a child.

About one in seven women of reproductive age with private health insurance in the United States takes an antidepressant, according to Jennita Reefhuis and Jennifer N. Lind, co-authors of Centers for Disease Control and Prevention research into this matter. More recent data suggest that about 3% of pregnant women may be taking antidepressants during pregnancy, noted Reefhuis and Lind.

Not all scientists agree with these estimates. For instance, Berard says the literature shows "that antidepressants are amongst the most used prescription during pregnancy. Around 14% to 16% of pregnant women will take an antidepressant during pregnancy in the USA, mostly SSRIs."

Brown and his co-authors estimate the current prevalence among pregnant women between 4% and 10%.

Disagreement about the numbers aside, some women undoubtedly take SSRIs during pregnancy, yet this decision is not a simple matter, said Brown.

Psychotherapy can be as effective as antidepressants in treating moderate or milder forms of depression, but more severe forms of depression, including suicidal depression and psychotic depression, are an entirely different matter, he explained. The potential risks when a pregnant woman who suffers from a severe form of depression tapers off her medication could easily outweigh the benefits gained, according to Brown.

"Many women need to take antidepressants during pregnancy," said Reefhuis and Lind, who advocate discussing the matter of other treatment options with health care providers as helpful to women who want to make informed decisions.

Join the conversation See the latest news and share your comments with CNN Health on Facebook and Twitter.

This view is supported by Brown, though he added that antidepressant use during pregnancy has also been associated with neonatal adaptation syndrome (in which a baby suffers convulsions, tremors and poor feeding, among other symptoms) and depression at the beginning of adolescence.