S.D. Codified Laws § 58-18-34
An insurer may require notice that a newly born or newly adopted child is to be added to the policy or that coverage is to be changed from single or spousal coverage to family coverage. However, the insurer may not require notification sooner than the birth of the child or the start of the adoption bonding period. If the child is added or coverage changed to family coverage before the birth of the child or the start of the adoption bonding period, no additional premium may be charged by the insurer until the birth of the child or the start of the adoption bonding period. The insurer shall take reasonable steps to provide adequate notice to insureds of the need to alter coverage to ensure newborn or adopted children are covered and of the lack of premium adjustment until the birth of the child or the start of the adoption bonding period. An insurer is considered to have taken reasonable steps if prominent disclosure of the requirements of this section are included in a certificate, subscriber contract, evidence of coverage, or employee handbook if such are provided to all insureds.
If payment of a specific premium or subscription fee is required to provide coverage for a child, the policy or contract may require that notification of birth of a newly born child or notification of the start of the six-month adoption bonding period for an adopted child or start of the bonding period and payment of the required premium or fees be furnished to the insurer or nonprofit service or indemnity corporation within thirty-one days after the date of birth or notification of the start of the six-month adoption bonding period for an adopted child or start of the bonding period in order to have the coverage continued beyond the thirty-one day period.
SDCL 58-18-34