In December, 1973, Carolyn C. Clevenger (plaintiff), the mother of two daughters, consulted the defendant, an obstetrician and gynecologist, for a physical examination and “to discuss having [her] tubes tied.” The defendant performed a tubal ligation on the plaintiff on January 10, 1974. The plaintiff s third daughter was born March 17, 1975.
The plaintiffs commenced this action, alleging negligence and breach of contract. The judge directed a verdict for the defendant on the negligence count, and the plaintiffs do not challenge that ruling in this appeal. The judge submitted the contract count to the jury, reserving leave to enter a verdict for the defendant notwithstanding a verdict in favor of the plaintiffs, and he also submitted interrogatories to the jury concerning the contract claim. The jury returned a verdict for the defendant, and the plaintiffs have appealed from a judgment for the defendant on that verdict. We conclude that the evidence did not warrant submitting the case to the jury on the contract count, even considering certain evidence which the judge excluded.2 Consequently, we need not pass on various issues that the plaintiffs have argued in this appeal, which we transferred here on our own motion.3
*156The evidence in this case, taken in its form most favorable to the plaintiffs, does not disclose an enforceable promise by the defendant that the plaintiff would not have another child. The only evidence on which a promise, guaranty, or warranty of a specific result could have been based is the testimony of the plaintiff as to what the defendant told her in the course of her initial visit to the defendant in December, 1973.4 Because the plaintiffs testimony concerning that conversation is crucial to the disposition of this appeal, we set it forth fully, omitting only one interruption when the witness started to recite what another physician had told her. The plaintiff testified: “Well, after the initial visit, I mean the initial examination, we went in and he said that I was in good health. And I said that I was interested in having my tubes tied. And he said, well, you know, that is not an operation that you go into lightly. And I said, I know. I said, I have had a lot of problems with my back. When I had my second child I had a back operation, as after I had my first baby and then I had problems delivering my second baby, and I was really frightened to have any more, and I — we couldn’t afford any more. And I said, I know that this is what I would like to do. He said, well, you know, this is a permanent thing. You are not going to have any more children after this operation. It is not something — have you discussed this with your husband? And I said, yes, we have had two years to think about it. I said, I wanted the operation done after [my second child], and I was too young at that time. The physician that I had at that time was Doctor Dorman, and he told me that — [interruption], ... So I waited two years, and was going to *157go back to the other doctor. I was afraid he wouldn’t do it, so I consulted [the defendant]. So he said we will do it. You are in good health, in reason, why not. As long as you know it’s a permanent thing. This is it. There is no reversal. You are not going to have any more children. I said, I know. That is what I want. I don’t want any more. He said he would make an appointment for the hospital and take care of things from there.”
The only other evidence that might bear on the question whether the defendant promised a specific result was certain postoperative conversations. These conversations could not have created an enforceable contractual obligation, but the evidence was arguably relevant as to the defendant’s state of mind at the time of the pre-operative conversation, as tending to show that the defendant had believed that after the operation the plaintiff would not be able to have a child. One postoperative conversation occurred in July, 1974, when the plaintiff telephoned the defendant.5 The judge ultimately struck this testimony on his own motion. Testimony of two conversations, also occurring in the summer of 1974, between the plaintiff’s mother and the defendant was also excluded.6 Even if all the excluded testimony had been admitted, the evidence would not have warranted a finding of a promise of a specific result.
In a recent discussion of a case involving a claim that a physician had contracted to achieve a particular medical result, we noted that actions based on such alleged contracts *158are allowed but that there must be “clear proof.” Sullivan v. O’Connor, 363 Mass. 579, 582-583 (1973).7 In Salem Orthopedic Surgeons, Inc. v. Quinn, 377 Mass. 514, 517 (1979), we characterized the Sullivan case as adopting the view that recovery may be had against a physician “who expressly agrees to produce a certain medical result and then, without fault, fails to do so” (emphasis supplied). Some courts have taken the position that there must be separate consideration for the physician’s promise,8 and at least one has adopted the view that a higher burden of proof (“clear and convincing evidence”) is required than in the normal civil action (Sard v. Hardy, 281 Md. 432, 453 [1977]). Some States require enforceable medical contracts to be in writing. See Note, Physicians and Surgeons — Sullivan v. O’Connor: A Liberal View of the Contractual Liability of Physicians and Surgeons, 54 N.C.L. Rev. 885, 902 n.102 (1976), citing statutes in Michigan, Ohio, and Pennsylvania.
“Clear proof” does not require proof of special consideration for the promise nor does it heighten the burden of proof. What it does require is that the trier of fact give *159attention to particular factors in deciding whether the physician made a statement which, in the context of the relationship, could have been reasonably interpreted by the patient as a promise that a given result or cure would be achieved. 9 The factors relevant in such an appraisal and their respective values or weights will vary with the circumstances of given cases. Some of the possible factors are noted in the Sullivan case. It should be regarded as a negative factor, although one not in itself determinative, that the physician and patient did not focus on the question whether the physician was undertaking to achieve a given result. The trier of fact should not adopt a relaxed attitude that might subject a physician to liability for making statements reasonably calculated only to reassure a patient or, as in this case, for stating the significant consequences that could be expected to follow upon a successful surgical procedure.
Here the defendant rightly emphasized the significance of a tubal ligation which, according to the testimony, is effective in the overwhelming percentage of the cases where the surgical procedure is carried out with due care.10 The defendant’s words were designed to make sure that the plaintiff knew the operation was non-reversible in character. See Rogala v. Silva, 16 Ill. App. 3d 63, 66-67 (1973). The parties did not focus on the question of a promise, nor were the words used promissory in nature. Doubt could be lessened or removed in such a case if the physician were to *160call attention to the possibility that the operation might not succeed despite all standard surgical precautions. But we are persuaded on the whole that the case for liability was not sufficiently demonstrated to warrant submission to the jury.
Judgment affirmed.
By submitting the case to the jury, reserving leave to enter a verdict for the defendant (see Mass. R. Civ. P. 50 [b], 365 Mass. 814 [1974]), the judge followed the appropriate and more efficient practice “in any but a plain case.” Soares v. Lakebille Baseball Camp, Inc., 369 Mass. 974, 975 (1976). Smith v. Ariens Co., 375 Mass. 620, 627 (1978). In this appeal, the verdict for the defendant on the contract count can rightly be sustained by a determination that the evidence did not warrant submission of that count to the jury.
One issue concerns the proper consequences of the jury’s answers to two interrogatories. They answered affirmatively to the question whether *156there was a contract between the plaintiff and the defendant “calling for a promised result that she would not have children in the future.” Then they answered negatively to the question whether the defendant did “breach that contract.” We need not decide whether these answers are irreconcilable or, if they are, whether the plaintiffs’ failure to object to the answers before the jury were discharged bars any right to challenge the jury’s verdict in this appeal.
The defendant testified that he had no memory of the details of any discussion with the plaintiff prior to the operation.
The plaintiff testified to this conversation as follows: “I told him that I wasn’t feeling well and that I was one week late with my period, and I said, do you think there could be a problem, and he said, no, don’t worry. I want to assure you there is no way that you can possibly be pregnant.”
The offer of proof was that the plaintiff s mother would testify that the defendant told her that it was impossible for the plaintiff to be pregnant. The judge excluded the testimony because it was hearsay, but offered to admit it if the plaintiff s counsel could provide a hearsay exception. No exception (such as that for an admission) was brought to the judge’s attention.
In that opinion, we noted that “[i]t is not hard to see why the courts should be unenthusiastic or skeptical about the contract theory. Considering the uncertainties of medical science and the variations in the physical and psychological conditions of individual patients, doctors can seldom in good faith promise specific results. Therefore it is unlikely that physicians of even average integrity will in fact make such promises. Statements of opinion by the physician with some optimistic coloring are a different thing, and may indeed have therapeutic value. But patients may transform such statements into firm promises in their own minds, especially when they have been disappointed in the event, and testify in that sense to sympathetic juries. If actions for breach of promise can be readily maintained, doctors, so it is said, will be frightened into practising ‘defensive medicine.’ On the other hand, if these actions were outlawed, leaving only the possibility of suits for malpractice, there is fear that the public might be exposed to the enticements of charlatans, and confidence in the profession might ultimately be shaken.” Sullivan v. O’Connor, 363 Mass. 579, 582-583 (1973) (citation and footnote omitted).
See, e.g., Rogala v. Silva, 16 Ill. App. 3d 63, 65 (1973); Sard v. Hardy, 281 Md. 432, 451 (1977).
Compare Custody of a Minor (No. 1), 377 Mass. 876, 884-886 (1979), an instance where the court rejected a “clear and convincing” standard intended to heighten the burden of proof, but called for specific findings by the judge to demonstrate that “close attention has been given the evidence” and that the conclusion reached “has been persuasively shown.”
There was uncontradicted expert testimony that pregnancies occur in some instances in spite of the nonnegligent performance of such an operation. The physician who delivered the plaintiff s third child and performed a second tubal ligation, but by a different procedure, testified that there is a rate of “failure” for all tubal ligation procedures which varies in the range of “one per two-hundred and fifty cases, one per five hundred, one per one thousand.”