This is an appeal from an order entered subsequent to a decree of divorce entered by default. We affirm.
In the 1975 decree of divorce the trial court ordered child support, alimony and division of marital property pursuant to a stipulation of the parties and an addendum to that stipulation. Appellee, E. James Hood, was responsible for medical insurance coverage on the children and also medical expenses not covered by insurance. For a period of time appellee fulfilled this obligation by paying a monthly premium of $40 on a health insurance policy for the two children. Later, appellant, Judith G. Hood, secured health insurance on the children through her employer at a monthly premium rate of seventy-five dollars. Child support was $150.00 per child per month. Alimony was $100.00 per month. Each succeeding year the amount of alimony and child support was to automatically increase pro rata in an amount equal to ten percent of appellee’s net income exceeding $12,-500.00. Upon appellant’s remarriage, her right to alimony ceased and any increase in appellee’s child support obligation was calculated at 7.5 percent rather than ten percent.
In 1982, appellee moved the circuit court to determine the amount of child support arrearages, if any, and to abate all or part of those arrearages. Appellee also asked the circuit court to abate his responsibility for prior medical expenses of the children. Appellant requested that her former husband be held in contempt for failure to pay child support and medical expenses as ordered in the divorce judgment. She also requested attorney fees and an increase in child support.
The trial court ordered that the parties were responsible for their own attorney fees, that appellee was responsible for the medical expenses incurred by appellant on behalf of the children, and that the parties make arrangements for payment of the same. The trial court also abated all child support arrearages, struck the provision providing for an automatic percentage increase in child support, and increased appel-lee’s future child support obligations to $175.00 per child per month.
*351ATTORNEY FEES
The trial court has the authority to award reasonable attorney fees and this Court will disturb the trial court’s decision only if there has been an abuse of discretion. Wallahan v. Wallahan, 284 N.W.2d 21 (S.D.1979). We find that the trial court did not abuse its discretion in ruling that each party should be responsible for their own attorney fees.
MEDICAL EXPENSES
We find no abuse of discretion in the trial court’s ruling that appellee continue to be responsible for the medical expenses of the children. Part of appellee’s responsibility for the medical expenses of the children was to provide medical insurance coverage. The trial court’s ruling that appellee was responsible for the medical expenses of the children changed nothing; therefore, implicit in that ruling is the requirement that he continue to reimburse appellant for the amount of the insurance premium he was paying prior to the change of insurance companies. If appellant elects to secure insurance coverage other than that provided by appellee, she may do so but she may not increase his obligation to pay the premium.
CHILD SUPPORT
The trial court has continuing jurisdiction to modify child support obligations. State ex rel. Larsgaard v. Lars-gaard, 298 N.W.2d 381 (S.D.1980). This power applies even though the child support obligation was created by agreement of the parties and later adopted by the Court. Johnson v. Lowary, 132 N.W.2d 823 (S.D. 1965). Child support obligations may also be modified retroactively. Larsgaard, supra.
The trial court found that the percentage increase in payments agreed to by the parties was actually alimony and therefore terminated upon appellant’s remarriage. This interpretation of a somewhat ambiguous agreement of the parties is not clearly incorrect and will therefore not be disturbed by this Court.
The most important factor which should be employed by trial courts in setting a child support obligation is the needs of the children. By this we mean the actual cost of providing food, clothing, shelter and the necessities of life. The needs of the children must then be apportioned between the parties based upon each parent’s ability to pay. When the amount of child support owing is determined simply by multiplying a party’s earnings by a percentage then “the myriad of possible changes aside from a party’s increased earnings that are relevant to the issue of quantum of child support” are ignored. Karim v. Karim, 290 N.W.2d 479 (S.D.1980). In short, it is inappropriate to provide automatic increases in child support based upon a percentage of the obligated parent’s income.
The order of the trial court is affirmed.
FOSHEIM, C.J., and DUNN and MORGAN, JJ., concur. WOLLMAN, J., dissents. ANDERSON, Circuit Judge, sitting for HENDERSON, J., disqualified.