MOORE, J.

The parties herein were married on October 29, 1945, and lived together as husband and wife until May 13, 1954. On May 27, 1954, they entered into the following agreement:

"This agreement made and entered into this 27th day of May, 1954, by and between Mary Lou Sorenson and Earl J. Sorenson.

"Whereas, the parties hereto are husband and wife and have two children, named Patricia L. Sorenson and Michael M. Sorenson, and

"Whereas, Mary Lou Sorenson contemplates filing suit for divorce.

"Now therefore, it is mutually agreed as follows:

"1. Out of the jointly owned property owned by the parties hereto, it is agreed that Earl J. Sorenson shall have the automobile and the jeep as his separate property. Mary Lou Sorenson shall have one half of the dishes and one half of the linens and clothing for herself and the children. The balance of the household goods will be sold and used to pay off joint indebtedness.

"2. It is agreed that Mary Lou Sorenson shall have absolute care and custody of the children, Patricia L. and Michael M. Sorenson, subject to the rights of visitation hereinafter set out.

"3. Earl J. Sorenson agrees to pay $50 per month for the care and support of both children. Earl J. Sorenson agrees to pay one half of the cost of obtaining a divorce.

"4. It is agreed that Earl J. Sorenson will have rights of reasonable visitation with the children at all times and will be entitled to have the children with him for one week during each summer, and to have them for weekends when agreeable to the parties hereto.

"In witness whereof, the parties hereto have signed their names this 27th day of May, 1954.

WITNESS: (s) Mary Lou Sorenson (s) William O. Lewis (s) Earl J. Sorenson

On November 3, 1954, plaintiff obtained a decree of divorce on grounds of cruel and inhuman treatment which was approved as to form by G.O. Hurley, defendant's attorney. The decree makes the May 27 agreement a part thereof and includes orders as to custody, visitations and child support in accordance therewith.

This is an action by plaintiff to modify the child support and visitation terms of the decree and seeking to impress a trust on certain property inherited by defendant. In her application filed June 9, 1960, plaintiff alleged defendant's earnings had greatly increased since the decree and defendant was about to receive two thirds of his mother's estate, estimated at $49,430.30, which was then being probated. She also stated the requirements of Patricia and Michael, then ages 11 and 9 years, for support and maintenance had greatly increased. She asked the child support be increased to $90 per month and that a trust be impressed on defendant's property to enforce payment of child support due under the provisions of the decree none of which had been paid.

On September 10, 1960, defendant filed his answer and resistance pleading substantially the same defense as set out in his amended and substituted answer and resistance. On March 31, 1961, defendant filed amended and substituted answer and resistance to application in which he requested in separate divisions the stipulation and decree be modified in respect to paternity and child support. He claimed plaintiff fraudulently obtained the stipulation and decree, was estopped from collecting past or future child support, by agreement had waived child support provisions, and he had no duty to support said children.

The trial started on March 31, and therefore plaintiff was given time to file motions and her reply. Thereafter she filed a motion to strike all allegations in regard to the paternity of the two children contained in the amended and substituted answer of defendant upon the grounds that said matter was res judicata, that defendant by signing the property settlement and stipulation assumed the responsibility for the support of said children and was estopped from denying their paternity.

The motion to strike was taken with the submission of the issues raised by the pleadings, including plaintiff's reply in which she denied defendant's allegations.

In the findings, conclusions and decree the trial court found: (1) The issue of paternity of the two children was res judicata as to defendant and the original decree was binding upon him in this respect, (2) there was no fraud or deceit on plaintiff's part in the matter of execution of the stipulation, (3) defendant was the children's father, (4) there was no agreement or conduct on plaintiff's part waiving child support, and (5) because of substantial change of circumstances arising since entry of the original decree the child support payments should be increased to $70 per month. Plaintiff's request to establish a trust was denied.

Defendant relies on three propositions for reversal. (1) The evidence clearly discloses he is not the father of the children. (2) Defendant proved fraud and deceit by plaintiff justifying the vacating and setting aside of the stipulation and decree. (3) The evidence established a binding oral contract between the parties to release defendant from child support payments.

I. We consider first the question of defendant's claim the stipulation and terms of the original decree establishing paternity should be set aside or modified because of fraud and deceit.

On direct examination defendant testified:

"I have lived in Council Bluffs going on three years. At all times since I moved to Council Bluffs I have had a telephone, and my name has been in the telephone directory. After the divorce, until 1958 I lived on my mother's farm near Harlan; and moved from there to Council Bluffs. I have never been in California since the divorce and have been in the State of Iowa all the time. Within two or three weeks after the date of the decree I had a conversation with my former wife, now Mrs. Huffman. Up to that time I had not seen the children. * * * On the way down to Omaha I saw her on the street in Council Bluffs and I stopped and talked to her and asked her about visiting the children and she said no and I said well I had my rights by decree that I should visit the children and she said well she didn't want me to visit the children and I said if that was the case I was going to try to get custody of the children and she said well you don't need to bother. Them ain't your children anyhow. You're not the father. * * * I have not ever paid any support money. At that time also she told me she was going to marry Mr. Huffman and he would support the children and that she did not need any of my help. In relation to visiting the children, she said it would cause trouble and she did not want me to visit them. The last and only time that I have seen the children since the divorce was at my mother's funeral and I didn't get to talk to them. * * * I haven't seen my former wife since the divorce and she hasn't phoned me. On one occasion when the children were to visit my mother, I was asked to leave because of instructions that my former wife had left with Ed Christensen and I did not get to see the children. I have been examined by Dr. Joseph Spearing to determine whether I could be the father of children. Neither my former wife nor Mr. Huffman have ever made any demand upon me for assistance in taking care of the children. At no time did my mother ever mention receiving a letter from my former wife relating to one of the children needing glasses."

On cross-examination defendant testified:

"During my marriage with Mary Lou, I had normal sex relations with her and these continued up to the time of our separation sometime in '54.

"After my divorce I lived at my mother's and was home every night. She gave me some financial help, as she had done through my married life. Through the years of marriage I thought I was the father of the children. * * *

"I was never examined as to my sterility prior to October 25, 1960, and have not been examined by other doctors."

Having testified in her case in chief regarding the change of circumstances in defendant's earnings, the children's increased support requirements and defendant's inheritance, on rebuttal plaintiff testified:

"The first inquiry as to the whereabouts of Earl I made about two years ago, by asking his mother. I had heard that Earl had gone to California but had never spoken to his mother or stepfather regarding that. We didn't hear anything for quite awhile and we assumed he was still out in California. Earl never told me he was going to try and get custody and I never had conversation with him on the street in Council Bluffs. I never told him he couldn't visit the children. Within a short period after we signed the stipulation he told me he was not going to contribute support. I have never told Earl that the children were not his. I once did write a letter to his mother regarding Earl's whereabouts, and they came down and talked to us. Ed told me he had been asked to leave out there, that he didn't know where he had gone to, but he would tell me if he ever found out. But he never did. This was some time before Mrs. Christensen's death. I was having normal sex relations with Earl at the probable time of conception of both Pat and Mike. I had normal sex relations with Earl during the married life, but not with other men. I don't believe he ever used preventives and I never did.

"After the decree I knew that I could require Earl to pay the support money, but I don't think the laws were as strict as they are now with fathers that don't. I talked to a lawyer once about it and he thought it would be almost impossible to get him to pay any money. At the time I don't know whether Earl had any income, or was regularly employed."

On cross-examination she testified:

"Earl said he wasn't going to pay support money for the children after we had signed the stipulation at Mr. Lewis' office, and before the decree was entered. I at no time told Earl I was going to marry Mr. Huffman, but at the time of signing I didn't exactly know I was going to marry him. At no time did I make inquiry of any of Earl's friends who were my mutual friends, as to where he might have been. Actually, I never paid any attention trying to find him. He would have been free to see the children if he had paid the support money, but not otherwise."

The evidence also shows plaintiff married Eldwin Arthur Huffman a short time after the divorce and that three children were born as issue of this marriage. Since plaintiff's remarriage Patricia and Michael have lived in the Huffman home. Defendant has also remarried.

[1, 2] In the first sentence of each division of defendant's application he pleads: "by way of application for further modification of the decree of divorce as to custody and child support * * *." Literal construction would indicate he sought relief as authorized by Code section 598.14. We have repeatedly held in construing this section that only where a change of circumstances is shown since the decree may a modification be made. Pearson v. Pearson, 247 Iowa 437, 74 N.W.2d 224; Herb v. Herb, 251 Iowa 957, 103 N.W.2d 361. Defendant offered no evidence of change of circumstances since the decree nor does he so argue. If he pursued such a course then he would recognize the decree as a binding adjudication as of the date rendered. Pedersen v. Pedersen, 235 Iowa 708, 17 N.W.2d 520, and citations. Defendant's real claim is that plaintiff practiced fraud in obtaining the decree. He seeks to set aside its provision as to paternity and child support and to relitigate those issues. We therefore consider his contentions on that basis.

Rule 252, R.C.P., provides:

"Judgment vacated or modified — grounds. Upon timely petition and notice under rule 253 the court may correct, vacate or modify a final judgment or order, or grant a new trial on any of the following grounds: * * *

"(b) Irregularity or fraud practiced in obtaining the same; * * *."

Rule 253, R.C.P., provides:

"Petition, notice, trial. (a) Petition. A petition for relief under rule 252 must be filed in the original action within one year after the rendition of the judgment or order involved.* * *."

[3, 4] Defendant cannot bring himself within the provisions of rules 252 and 253 because he did not act within the one-year limit therein provided and seeks to vacate or modify the decree upon equitable grounds. We have held the remedy under the rules or earlier statutes is not exclusive, when the fraud is not discovered within the year and that, in such cases, courts of equity have jurisdiction to grant new trials independently of the rule or statute. Graves v. Graves, 132 Iowa 199, 109 N.W. 707, 10 L.R.A., N.S., 216, 10 Ann. Cas. 1104; Tollefson v. Tollefson, 137 Iowa 151, 114 N.W. 631; Sudbury v. Sudbury, 179 Iowa 1039, 162 N.W. 209; Pedersen v. Pedersen, 235 Iowa 708, 17 N.W.2d 520. But the fraud which will authorize the granting of a new trial under this rule must be extrinsic or collateral to the matter directly involved in the original case. Scheel v. Superior Mfg. Co., 249 Iowa 873, 89 N.W.2d 377, and citations. We will assume, without deciding, the fraud claimed by defendant was extrinsic.

[5] It is a well established rule that if alleged fraud by use of reasonable diligence might have been discovered within the one-year limitation then applicant should not be allowed to prosecute the proceeding in equity. Graves v. Graves, 132 Iowa 199, 109 N.W. 707, 10 L.R.A., N.S., 216, 10 Ann. Cas. 1104; Pedersen v. Pedersen, 235 Iowa 708, 17 N.W.2d 520. In the Graves case at pages 205, 206 of 132 Iowa, page 709 of 109 N.W., it is said:

"Of course, if plaintiff discovered the alleged fraud and false swearing within a year, or, by the use of reasonable diligence on her part might have discovered it within that time, she should not be allowed to prosecute this proceeding in equity."

Defendant's testimony not only shows actual knowledge of the alleged fraud within three weeks after entry of the decree but also clearly establishes defendant's failure to exercise ordinary diligence. This alone bars his attempt here to litigate the issues of paternity and child support but his appeal to equity will be considered.

[6] We have held several times that a party against whom a decree of divorce is granted may be barred by laches or estoppel from attacking it. See Hurley v. Hurley, 117 Iowa 621, 91 N.W. 895; Farr v. Farr, 190 Iowa 1005, 181 N.W. 268; Robson v. Kramer, 215 Iowa 973, 245 N.W. 341; Swift v. Swift, 239 Iowa 62, 69, 70, 29 N.W.2d 535. In the Swift case it is said:

[7] "Courts are disposed to protect an innocent third person who has married a divorced spouse, also to protect possible issue of such marriage, and manifest reluctance to set aside the divorce. Rush v. Rush, 46 Iowa 648, 650, 26 Am. Rep. 179; annotation 157 A.L.R. 6, 51, 52; 27 C.J.S., Divorce, section 171a.

"In a controversy of this kind the court is concerned not alone with the rights of the individuals involved but also with the public interest. Hamilton v. McNeill, 150 Iowa 470, 478, 129 N.W. 480, Ann Cas. 1912d 604; Walters v. Walters, 151 Minn. 300, 186 N.W. 693, 694; annotation L.R.A. 1917B, 409, 413, 414. See, also, Hopping v. Hopping, 233 Iowa 993, 996, 10 N.W.2d 87, 89, 90, 152 A.L.R. 436, 439. In many situations it may be in the public interest to recognize an invalid divorce and preserve a remarriage rather than to resort to a dubious attempt to resurrect the original marriage. * * *

"The safety of society demands that one who seeks to overthrow an apparently valid decree of divorce should proceed with the utmost promptness upon discovery of facts claimed to show its invalidity. He should apprehend that one who has secured such a divorce may endeavor to marry again, thus entangling some innocent person in intolerable difficulties, should the divorce be afterwards annulled."

[8] If defendant's testimony, which stands alone and is denied by plaintiff, is to be believed he had notice within three weeks after the decree of the issue of paternity now being asserted by him. Thereafter plaintiff married Eldwin Arthur Huffman to which union three children have been born. Good conscience will not allow a court of equity to permit defendant's late attempt to bastardize the two children Patricia and Michael. We hold defendant is precluded by laches and estoppel from challenging the provisions of the decree establishing paternity of the two children.

The testimony of medical doctors, including opinions expressed by them, is in conflict. It goes to the issues of paternity and was taken over proper objections by plaintiff. In view of our holdings herein and for obvious reasons it is omitted from this opinion.

Our holdings make further consideration of the first two propositions argued unnecessary.

II. The third proposition argued by defendant is that the evidence establishes a binding oral agreement between the parties releasing him from child support. In Erwin v. Erwin, 251 Iowa 1344, 1345, 105 N.W.2d 489, 491, it is said:

[9] "It is well settled in this jurisdiction that divorced parents may contract between themselves as to the support of their minor child, if the best interest of the child is not injured thereby. Pappas v. Pappas, 247 Iowa 638, 75 N.W.2d 264, 57 A.L.R.2d 1134, and citations; Merkel v. Merkel, 247 Iowa 495, 73 N.W.2d 75; 39 Am. Jur., Parent and Child, section 42, page 653; 67 C.J.S., Parent and Child, section 15, page 697."

At page 1348, 251 Iowa, page 492, 105 N.W.2d, it is said:

"It is unnecessary that the proof of the oral contract be undisputed or be established as an absolute certainty. Reasonable certainty is sufficient. Williams v. Chapman, 242 Iowa 294, 307-309, 46 N.W.2d 56, 63, 64, and citations."

In Merkel v. Merkel, supra, the facts were undisputed. A written agreement was shown. In Pappas v. Pappas, supra, a written receipt and statement was established. In Erwin v. Erwin, supra, several persons testified to the agreement releasing the father from payment of child support. In each of these cases we held the proof sufficient.

[10] We have no such proof in this case. Only defendant's testimony was offered in his attempt to prove an agreement. It falls short of proving with reasonable certainty the alleged agreement. Indeed his testimony hardly indicates so much as an offer. When taken with plaintiff's denial of any such agreement it is clear the trial court properly ruled no agreement had been established.

After a careful study of the record, including the decree, we find no error. — Affirmed.

All JUSTICES concur except PETERSON, J., who takes no part.