Your question cannot be answered with the information available.
How old was your daughter when she became pregnant?
How old was the father?
The state of Mississippi revised the statutory rape laws in 1998 and is again revising them, so it is possible depending on their respective ages that that may play a role. Also the state of Mississippi recognizes they have a severe problem with teenage pregnancy and that situations where there the family is not intact have a higher incidence of teenage pregnancy, due in part to a lack of supervision.
The state of Mississippi does not have a statute specifically covering emacipation of "pregnant" minors, but at the same time acknowledges her right to "consent" (see below) as an adult for the care of her child, this would include maternity care and the laws srrounding paternity effectively are the same whether the "parents" are married or minors, also the minor father and or his family will have some responsibility once paternity is established, so it is possible that there may be defenses that would at least offset some of your responsibility.
If it is true that you were providing medical insurance and paying the co-pay in good faith and the mother refused to use the insurance, obtained unauthorized services informing you after the fact and you srill paid the entire bill you may have had grounds for contempt, also grounds for contempt for the lack of visitation you have had since your divorce, you will need to see an attorney to protect your interest, the laws are not specific to your case.
Obviously, your ex's supervision of the child was lax and she failed to even provide adequate medical care, which you were paying for when billed because of her violation of the agreement around medical care and as such she failed to obtain birth control for your daughter or B/C education which could have been obtained free or at low cost at a Planned Parenthood office. Most health departments and other programs provide condoms free of charge.
If she obtained medicad as an "emancipated minor" as allowed in Mississippi, it is possible you may not be responsible for it as she was exercising her right as a parent. If she had asked you to provide matenity care as she asked for other types of care, you would have paid it or obtained insurance, right? If you had been allowed visitation or to be a part of your daughter's life you might have had the opportunity to intervene.
I hope this helps point you to some possible answers to your question since you have more information.
MISSISSIPPI CODE OF 1972 As Amended
SEC. 41-41-3. Who may consent to surgical or medical treatment or procedures.
It is hereby recognized and established that, in addition to such other persons as may be so authorized and empowered, any one of the following persons is authorized and empowered to consent, either orally or otherwise, to any surgical or medical treatment or procedures not prohibited by law which may be suggested, recommended, prescribed or directed by a duly licensed physician:
(a) Any adult, for himself. For purposes of this section, the term "adult" shall mean any person who is eighteen (18) years of age or older.
(b) Any parent, whether an adult or a minor, for his minor child or for his adult child of unsound mind; however, the father of an illegitimate child cannot consent for said child solely on the basis of parenthood.
(c) Any married person, whether an adult or a minor, for himself, and, where his joinder in the consent of his spouse may be desired or required, with his spouse.
(d) Any married person, whether an adult or a minor, for his spouse of unsound mind.
(e) Any person standing in loco parentis, whether formally serving or not, and any guardian, conservator or custodian, for his ward or other charge under disability.
(f) Any adult for his father or mother of unsound mind; however, an illegitimate child cannot consent for his natural father solely on the basis of the latter's parenthood.
(g) Any emancipated minor, for himself.
(h) Any unemancipated minor of sufficient intelligence to understand and appreciate the consequences of the proposed surgical or medical treatment or procedures, for himself.
(i) Any female, regardless of age or marital status, for herself when given in connection with pregnancy or childbirth.
(j) Any adult, for his minor brother or sister or for his adult brother or sister of unsound mind.
(k) During the absence of a parent so authorized and empowered, any maternal grandparent and, if the father be so authorized and empowered and be of legitimate birth, any paternal grandparent, for his minor grandchild or for his adult grandchild of unsound mind.
However, no person so authorized and empowered may arbitrarily, obstinately or without reasonable medical justification withhold or refuse his consent. However, nothing contained herein shall be construed to abridge any right of an adult who is not of unsound mind, who is not pregnant, whose wife is not pregnant, and who is not the parent of a minor living child, to refuse such consent as to his own person.
In addition to its usual definitions, the phrase "unsound mind" shall also mean and include, for the purposes of sections 41-41-3 through 41-41-11, a state of mind during which the person affected is unable to understand and appreciate the consequences of the proposed surgical or medical treatment or procedures so as to intelligently determine whether or not to consent to the same, regardless of whether such state of mind is only temporary or has existed for an extended period of time or occurs or has occurred only intermittently and whether or not it is due to natural state, age, shock or anxiety, illness, injury, drugs or sedation, intoxication or other cause of whatever nature.
SOURCES: Codes, 1942, Sec. 7129-81; Laws, 1966, ch. 478, Sec. 1; 1984, ch. 347, eff from and after July 1, 1984.