What medication should be administered to promote labor in a client whose cervix is not dilated?

Dinoprostone is an appropriate medication for promoting labor in a client whose cervix is not yet dilated because it helps to ripen the cervix, which means it enhances the cervical condition to allow for dilation and effacement. This prostaglandin analog works by causing the cervix to soften, thin, and open, making it ready for labor.

While oxytocin can induce contractions, it requires the cervix to be somewhat favorable for labor to be effective. Misoprostol also helps in cervical ripening and can be used for labor induction, but specifically in cases where there's a need to address not just the cervical readiness but also enhance uterine contractions. Terbutaline is a tocolytic, which is used to stop contractions rather than to promote labor, making it unsuitable for this purpose.

Thus, dinoprostone is ideal for initiating labor by focusing on preparing the cervix in cases where it has not yet begun to dilate.