Hello and welcome to healthcaremagic
Hormonal fluctuations during pregnancy could give rise to acne. Acne commonly resolves with
postinflammatory hyperpigmentation. Darkness of face during pregnancy could be related to high ACTH levels giving rise to melasma.
If I was the treating doctor I would suggest you to use a topical antibacterial e.g
clindamycin gel for day time use over active acne,
At night you could use a cream containing Azaleic acid 20% over the whole affected area, overnight. Azaleic acid is a topical retinoid, it is antibacterial, comedolytic as well as antiinflamatory. It also inhibits melanin synthesis through inhibition of tyrosinase enzyme. Therefore it would work for both acne as well as post-inflammatory hyperpigmentation as well as melasma.
If you have inflammatory acne, I would prefer to start you on
oral antibiotics e.g either doxycycline or
azithromycin or
minocycline.
Always use a broad spectrum sunscreen, that which offers both UV B as well as UV A protection, throughout the day, to prevent further sun induced darkening.
Regards