Plaintiff appeals from the adjudication that he is the father of defendant’s child, Rhonda. Defendant appeals from the judgment dismissing her cross action and from the decree awarding plaintiff an absolute divorce.

Plaintiff’s complaint alleges a cause of action for divorce on the ground of one year’s separation. G.S. 50-6. Defendant’s answer denies the separation as alleged and sets up a cross action for alimony without divorce upon allegations that plaintiff had abandoned her and their child, born after plaintiff had separated himself from defendant. G.S. 50-16. By reply plaintiff denies defendant’s allegations of abandonment ánd paternity and, in bar of alimony, pleads that the agreement of 10 March 1965 had legalized their separation from that date and released him from any further obligation to defendant. By rebutter, defendant pleads the invalidity of the separation agreement. This method of pleading was approved in Lawson v. Bennett, 240 N.C. 52, 81 S.E. 2d 162.

In addition to her allegation that the deed of separation had been rescinded by subsequent sexual relations, Jones v. Lewis, 243 N.C. 259, 90 S.E. 2d 547, defendant alleges that it was invalid'because (a) at the time she executed it she was an infant, 17vye&is of age; (b) she lacked .sufficient .mental capacity., to,•.'execute ,.the. instrument; .and (c) the agreement! yras" fraudulently obtained'and grossly unfair to her.'

Until the deed of separation is rescinded, defendant cannot attack the legality of the separation or obtain alimony from plaintiff. O’Brien v. O’Brien, 266 N.C. 502, 146 S.E. 2d 500; Edmisten v. Edmisten, 265 N.C. 488, 144 S.E. 2d 404; Fuchs v. Fuchs, 260 N.C. 635, 133 S.E. 2d 487. A married woman may attack 'thevcertificate of her acknowledgment and privy examination respecting her execution of a deed of séparation, inter alia, upon the grounds, of her mental incapacity, infancy, or the fraud of the grantee. Lee v. Rhodes, 230 N.C. 190, 52 S.E. 2d 674. See Van Every v. Van Every, 265 N.C. 506, 144 S.E. 2d 603; Joyner v. Joyner, 264 N.C. 27, 140 S.E. 2d 714; Lawson v. Bennett, supra.

Defendant’s evidence tended to show that at the time she signed the deed of separation, she was an infant 17 years of age. Absent an enabling statute which provides a different rulé, an infant’s contract with his or her spouse is subject to the general principle that the deeds and contracts of an infant (except for a narrowly limited class of contracts not applicable here) are voidable at his election within a reasonable time after he comes of age. 27 Am. Jur. Infants § 16; 3 Lee, N. C. Family Law § 270 (1963); Fisher v. Motor Co., 249[*195] N.C. 617, 107 S.E. 2d 94; Jackson v. Beard, 162 N.C. 105, 78 S.E. 6.

Since 3 June 1965, G.S. 52-10.1 has empowered any married couple, both of whom are 18 years of age or over, to execute a binding separation agreement upon compliance with' its terms. In no event could this statute have any application to the agreement in suit, which was acknowledged 11 March 1965, At that time, the applicable statute, G.S. 52-13 (now G.S. 52-10), provided that “any persons of full age about to be married, and, subject to § 52-12 (now 52-6), any married person, may release and quitclaim such rights which they might respectively acquire or may have acquired by marriage in the property of each other. . . .” However, it was held in Motley v. Motley, 255 N.C. 190, 120 S.E. 2d 422, “that the foregoing statute (G.S. 52-13) relates to the release of an interest in property, but has no bearing whatever on the right of a wife to. support.” Id. at 193, 120 S.E. 2d at 424. (Emphasis added.)

In defendant’s rebutter, she has pled her infancy and prayed that the deed of separation be declared null and void. Even if G.S. 52-13 be construed as empowering all married minors to'release their rights in the property of their spouses, it did not authorize the minor wife to release her right to support, and her prayer that the deed of separation be declared null and void was a sufficient disaffirmance of the agreement insofar as it purported to release plaintiff from this obligation. Millsaps v. Estes, 137 N.C. 535, 542, 50 S.E. 227, 229.

With reference to her pleas that she lacked sufficient mental capacity to execute the agreement, and that it was unfair and fraudulent as to her, defendant’s evidence, taken in the light most favorable to her, was sufficient to establish these facts: She was mentally disturbed, and plaintiff, who had made an appointment with a psychiatrist to see defendant on 22 March 1965, well knew her condition. Notwithstanding, on 11 March 1965, he took her to the office of his attorney where, for $100.00 in cash, she was induced to sign a deed of separation releasing plaintiff from all obligation to support her and waiving all her interest in his property. Defendant had no attorney to advise her.

From the foregoing facts, the jury could find that at the time defendant signed the separation agreement she lacked the mental capacity to understand the nature of the act in which she was engaged, its scope and consequences; that the agreement was grossly unfair to her; and that she had been overreached. Goins v. McLoud, 231 N.C. 655, 58 S.E. 2d 634.

The relationship between husband and wife is the most confidential of all relationships, and transactions between.them, to be valid,[*196] must be fair and reasonable. Fulp v. Fulp, 264 N.C. 20, 140 S.E. 2d 708. Under the circumstances disclosed by this record, an inference of fraud arises from plaintiff’s dealings with his minor, mentally disturbed wife. To be valid, “a separation agreement must be untainted by fraud, must be in all respects fair, reasonable and just, and must have been entered into without coercion or the exercise of undue influence, and with full knowledge of all the circumstances, conditions, and rights of the contracting parties.” Taylor v. Taylor, 197 N.C. 197, 201, 148 S.E. 171, 173.

Defendant’s evidence was also plenary to support a finding by the jury that plaintiff, without just cause, abandoned defendant on 6 March 1965, as alleged. Richardson v. Richardson, 268 N.C. 538, 151 S.E. 2d 12. Where the husband sues the wife under G.S. 50-6 for an absolute divorce on the ground of one year’s separation, she may defeat his action by alleging and proving that the separation was caused by his abandonment of her. O’Brien v. O’Brien, supra; Taylor v. Taylor, 257 N.C. 130, 125 S.E. 2d 373. Had the issue of abandonment been submitted to the jury — as it should have been — when the issues in the divorce action were submitted, an affirmative answer to it would have precluded plaintiff’s divorce. Plaintiff’s action for divorce, the issue of the paternity of the child Rhonda, and defendant’s cross action for alimony cannot be separated. These issues, which determine the rights of the parties, are so interrelated that they must be decided in one action.

The court erred in dismissing defendant’s cross action. This error made any further proceedings in plaintiff’s action for divorce likewise erroneous. Defendant’s assignments of error must be sustained.

Plaintiff’s appeal and assignments of error bear upon the fourth issue, the jury’s answer to which established that he was the father of the child Rhonda, born 7 January 1966. If the fourth issue be answered Yes, the fifth must also be answered in the affirmative, since plaintiff admits he has never supported the child and denies his responsibility.

The usually accepted average period of pregnancy is 280 days. 2 Taylor, Principles and Practice of Medical Jurisprudence 24 (12th Ed. 1965). “[I]n the absence of evidence to the contrary, the term of pregnancy is presumed to be ten lunar months or 280 days. . . . Whether, according to the laws of nature, the term of pregnancy may extend 322 days or more from the moment of conception, is a proper subject of testimony by qualified medical experts.” Byerly v. Tolbert, 250 N.C. 27, 34-35, 108 S.E. 2d 29, 35. Protracted pregnancies of more than 280 days, while uncommon, are not considered[*197] extraordinary. Schatkin, Disputed Paternity Proceedings 519-538 (3d Ed. 1953); 3 Lee, N. C. Family Law § 250 (3d Ed. 1963).

When a child is born in wedlock, the law presumes it to be legitimate, and this presumption can be rebutted only by facts and circumstances which show that the husband could not have been the father, as that he was impotent or could not have had access to his wife. State v. McDowell, 101 N.C. 734, 736, 7 S.E. 785, 786, quoted with approval in State v. Rogers, 260 N.C. 406, 408, 133 S.E. 2d 1, 2; accord, State v. Tedder, 258 N.C. 64, 127 S.E. 2d 786; State v. Green, 210 N.C. 162, 185 S.E. 670. To render the child of a married woman illegitimate, unless impotency be established, proof of the nonaccess of her husband is required, and neither the wife nor the husband is a competent witness to prove such nonaccess. Ray v. Ray, 219 N.C. 217, 13 S.E. 2d 224. “The evidence of nonaccess, if there be such, must come from third persons." State v. Wade, 264 N.C. 144, 145, 141 S.E. 2d 34, 35. If there was access, there is a conclusive presumption that the child was lawfully begotten in wedlock. Ray v. Ray, supra; Ewell v. Ewell, 163 N.C. 233, 79 S.E. 509; Rhyne v. Hoffman, 59 N.C. 335. However, even though the husband, residing in the same community, had the opportunity of access, “[t]hat the wife is notoriously living in open adultery is a potent circumstance tending to show nonaccess,” for it is unreasonable to suppose that, under those circumstances, he would avail himself of such opportunity. Ray v. Ray, supra at 220, 13 S.E. 2d at 226.

This record is devoid of any evidence that defendant has committed any act of adultery. At the conclusion of defendant’s evidence, however, counsel for plaintiff informed the court that he “would like to offer some additional evidence on the question, of paternity.” The court declined to permit plaintiff to offer such evidence, and plaintiff assigns this ruling as error. The record does not disclose the identity of the proposed witnesses or what their testimony would have been. It cannot be determined, therefore, whether either the witness or his testimony would have been competent. “Failure to show what the witness would have answered renders the ruling nonprejudicial.” Westmoreland v. R. R., 253 N.C. 197, 198, 116 S.E. 2d 350, 351. Notwithstanding, for the reasons hereinafter indicated, the jury’s answer to the fourth issue must be set aside.

To entitle plaintiff to an absolute divorce, he was required to prove that he and defendant had lived continuously separate and apart for at least one year next preceding the institution of this action on 21 March 1966. On this record, the law presumes that plaintiff is the father of Rhonda and that she was conceived on or about 3 April 1965, a time within the year next preceding the institution of[*198] the action. Yet the court peremptorily instructed the jury that if they found the facts to be as all the evidence tended to show, they would answer the third issue Yes. As plaintiff correctly points out, “We have the anomalous situation of a jury determination that the parties have lived continuously separate and apart from each other during the period of gestation but that one of the parties is the father of the child of the other party.” On this record, the third and fourth issues may not each be answered Yes, and the court should have instructed the jury that if they answered the third issue Yes, they would answer the fourth issue No.

Fundamental error pervaded the trial of this case. Since the judgments dismissing defendant’s cross action and awarding plaintiff an absolute divorce must be set aside, justice requires that the adjudication of paternity likewise be vacated and that a trial de novo be had on all issues raised by the pleadings. Defendant’s pleadings are minimal. If so advised, she may move for permission to re-plead.

The decision is this: On defendant’s appeal, the judgment dismissing the cross action is reversed; the decree of absolute divorce is vacated and a new trial ordered. On plaintiff’s appeal, the adjudication of paternity is set aside and a new trial ordered.

Plaintiff’s appeal,

New .trial.

Defendant’s appeal,

Reversed and remanded.