Some reports of deaths from use of the birth control pill may have been exaggerated in the past few years.

And the risk of disease or death from pill use may be statistically small among most women, especially women under 35.

Still, the pill is far from innocuous. And women who take it should know that their risk of having a heart attack may be increased four-fold-or 39-fold if they also smoke.

These conclusions were stated in various parts of three somewhat conflicting reports yesterday, in the lattest attempts to sort out confusing statistics and tell women what they should or shouldn't do about oral contraception.

The final answers on the pill are not in. In particular, some scientists wonder whether slow-developing, pill-related cancers may soon begin to appear in women who began taking the pill in the 1960s, nearly 20 years ago.

Still, the new reports-one by Dr. Christopher Tietze, the other by a team headed by Dr. Mark Belsey-tend to be pro-pill, though both say they neigher prove nor disprove the harshest allegations about pill dangers. Both appear in journals of the generally pro-pill Planned Parenthood Federation.

The Third, more neutral report-by a Boston University group that surveys the safety of all drugs-appears in the Lancet, leading British medical journal.

Tietze is a biostatistician with the nonprofit Population Council; Belsey is a World Health Organization specialist in human reproduction.

Independently they examined some much-quoted British studies which found that women on the pill had some four times the normal death rate from cardiovascular diseases-heart attacks, strokes and pulmonary embolisms (blood clots reaching the lungs).

Tietze and Belsey found no evidence for these allegations in the mortality statistics of 21 countries, including the United States and Great Britain. With some exceptions, they said, death rates from these diseases have actually dropped among women as well as men in recent years.

An editorial accompanying the Tietze and Belsey articles asks "Where Are the Deaths?" if the pill is indeed deadly, and charges that "there is evidence that headlines about pill-related deaths have driven many younger women from the pill to less effective methods," though "the dangers of pregnancy to life and health for such women are not insubstantial."

Tietze said in an interview he agreed with this view. But he also said he accepts the fact that there may be a four-fold increase in heart and blood vessel diseases among pill users-with a sharp rise among older users, especially smokers or those with other added "risk factors" like diabetes, hypertension, high cholesterol or, in some views, simple excess weight.

The boston group, headed by Drs. Samuel Shapiro and Dennis Slone, compared 234 premenopausal women who had suffered a myocardial infarction (heart attach) with 1,742 hospitalized non-users of the pill.

Almost exactly like the much-cited British groups, they found a probable four-fold rise in heart attacks among pill users and a 39-fold increase among pill-taking smokers. Yet the main risk, they said, is not among younger women but among women over 35, especially those who smoke more than 25 cigarettes daily or have other risk factors.

A Boston University scientist said the study indicates that "a nonpill-using, nonsmoking woman's risk of a heart attach each year is about four in 100,000, on the average, but 20 in 100,000 if she uses the pill-and twice that by her late 40s and 40 times higher if she smokes."

But excess deaths might be "hard and even impossible" to find, she added, in the kind of national mortality figures Tietze and Belsey examined, since "we-re adding small numbers of deaths to many thousands."

Dr. Sidney Wolfe, head of Ralph Nader's Health Research Group, said in Washington that the Tietze and Belsey studies contradict "17 years of accumulated work showing the pill's danders." He cited recent pieces of evidence that may implicate the pill in cervical cancer and noncancerous breast disorders that sometimes lead to cancer.

At the opposite pole, Tietze said he thinks unwarranted fright is resulting in "too little" use of the pill today.