Only a small fraction of contraceptives donated in Puerto Rico to prevent Zika-related birth defects are expected to get to the women who need them this month, public health officials told Reuters.

The donations - tens of thousands of intrauterine devices and birth control pill packs - came from major healthcare companies as the virus spreads rapidly through the island.

The delivery delays illustrate the struggles of Puerto Rico's healthcare system, which is faltering amid the commonwealth's financial crisis.