Defendant contends the trial court erred in decreeing that the .defendant owes the State of North Carolina $8,714.00 for public assistance paid as support for Michelle Tonya Ferrell. This Court notes from the outset that the State’s right to collect public *187monies expended through Aid to Families with Dependent Children for child support was legislatively created 1 July 1975. G.S. 110-128 et seq. The statute has the effect of subrogating the State to the rights of the dependent spouse to collect up to the amount expended.

Defendant argues on appeal that the doctrines of laches and equitable estoppel bar the State from initiating this action to collect funds expended six years prior. The doctrines of laches and equitable estoppel are affirmative defenses that must be set forth in the pleadings at trial. G.S. 1A-1, Rule 8(c), Rules of Civil Procedure. We have fully reviewed the record and fail to find any evidence that the defenses were raised in the pleadings or presented at trial. The issues may not now be raised for the first time on appeal. Starling v. Sproles, 69 N.C. App. 598, 318 S.E. 2d 94 (1984).

Defendant also contends that the court erred in requiring repayment of the costs of the blood tests. We disagree. The determination of this issue can only be resolved by reviewing the following three statutes: G.S. 8-50.1; G.S. 6-21; and G.S. 49-14, which speak to the question of illegitimate children and the taxing of the expense of blood tests as costs.

It is, of course, a fundamental canon of statutory construction that statutes which are in pari materia, i.e., which relate or are applicable to the same matter or subject, although enacted at different times must be construed together in order to ascertain legislative intent. (Citations omitted.)

Carver v. Carver, 310 N.C. 669, 674, 314 S.E. 2d 739, 742 (1984). The starting point in construing the statutes in the case sub judice is G.S. 8-50.1, which gives the trial judge the authority to order a blood test where the issue of parentage arises. The present action was commenced pursuant to Article 9, G.S. 110-128 et seq. which provide, inter alia, for Wake County to bring a civil action to determine paternity. G.S. 8-50.1 requires the party requesting the blood tests to be initially responsible for the costs; thereafter the statute provides that upon the entry of a verdict of parentage or non-parentage, the trial judge may tax the expenses for the blood tests and comparisons as costs in accordance with the provisions of G.S. 6-21. G.S. 8-50.1(b)(2).

*188G.S. 6-21(10) allows the costs in a proceeding regarding illegitimate children under Article 3, Chapter 49 of the General Statutes to be taxed against either party, or apportioned among the parties, in the discretion of the court. The County commenced this civil action to determine the paternity of an illegitimate child, thus coming within the purview of Article 3, Chapter 49. Article 3, Chapter 49 is applicable to civil actions regarding illegitimate children. Construing the three statutes together, we conclude that it was within the discretion of the trial judge to tax the costs of the blood test to the defendant.

As to the remaining contentions, defendant has failed to argue or cite any authority in their support, therefore, the contentions are deemed abandoned. Rule 28(b)(5), Rules of Appellate Procedure.

Affirmed.