Both mother and child are in good health.

Literal

Mother-child both healthy-[polite-です]

母子ともに = 'both mother and child' — 母子 (ぼし) is a compound noun, ともに = 'both/together.' 健全 (けんぜん) = healthy/sound — a more formal word than 元気. A phrase typically heard in medical or birth-announcement contexts.