Between 20 and 30 percent of women who undergo in vitro fertilization (IVF) procedures suffer from significant symptoms of depression.

Many practitioners believe that the hormone therapy involved in IVF procedures is primarily responsible for this. But new research from Tel Aviv University shows that, while this is true, other factors are even more influential.

According to Dr. Miki Bloch of Tel Aviv University's Sackler Faculty of Medicine and the Sourasky Medical Center in Tel Aviv, stress, pre-existing depression, and anxiety are more likely than hormone therapy to impact a woman's depression levels when undergoing IVF.

Combined, these factors may also affect IVF success rates -- so diagnosis and treatment of this depression is very important.

Recently reported in the Journal of Fertility and Sterility, Bloch's research clarifies the involvement of different hormonal states as triggers for depression during IVF, both for long- and short-term protocols.

In the long-term IVF protocol, women receive injections which block ovulation, resulting in a sharp decline in estrogen and progesterone levels.

This state continues for a two-week period before the patient is injected with hormones to stimulate ovulation, at which point the eggs are harvested and fertilized before being replanted into the womb.

The short-term IVF protocol does not include the initial two-week period of induction of a low hormonal state.

Women wanting to avoid potential depression may be advised by their doctors to go with the short-term protocol, as some doctors assume depression is more likely to occur due to those first two weeks of hormonal repression that goes with the long-term protocol.

But Bloch's research has demonstrated the difference between the two different procedures is negligible -- depression and anxiety rates for women who undergo the long protocol and short are exactly the same.

Bloch and his fellow researchers conducted a random assignment study, in which 108 women who came to the Sourasky Medical Center for IVF were randomly assigned to either the long- or short-term protocol.

They were given questionnaires and interviews at the start of the therapy and at four other points during the IVF treatment.

The results, said Bloch, show consistently increasing depression rates among patients in both groups, regardless of which protocol they underwent.

The first two weeks of hormonal repression had no impact on whether a woman experiences depression during IVF.

"Once the patient begins ovulating, her estrogen rises to high levels. Then, after the ovum is replanted in her uterus, there is a precipitous drop in these hormonal levels," he explains.

It's the severity of the estrogen drop, a feature of both protocols, that was found to affect the patient's emotional state.

What did have an effect, however, was the patients' stress and anxiety levels.

When compared to a "normal" population, women undergoing IVF experience very high levels of anxiety and depression even before the treatment begins.

And as the protocol advances, women experience increased anxiety about the success of the implantation.

Women who have a previous history of anxiety or depression disorders before the IVF treatment are even more susceptible.

According to Bloch, this is likely due to the fact that these women are more emotionally vulnerable to the toll of the IVF process, rather then increased reactivity to changing hormonal levels.

When it comes to depression rates, the type of protocol a patient undergoes, whether short-term or long-term, has no impact, Bloch concluded.

While doctors should look at their patient's individual needs when deciding on an IVF protocol, the current report suggests the type of protocol is not an important factor in the induction of depression.