The pregnant woman and 25 other migrants were aboard a vessel that was taking on water in the Atlantic Ocean when reached by the rescue boat Salvamar Gadir before daybreak today.
They were found 24 kilometres southwest of the Atlantic coastal town of Barbate, which lies between Cadiz and Gibraltar.
Emergency services for Spain's Andalucia region said the 20 men and six women were all of North African descent.
Another four boats carrying migrants who told Spanish authorities they were from Algeria were intercepted in the Mediterranean Sea.
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All the migrants were in good health, according to authorities.
Tens of thousands of migrants, mostly from sub-Saharan African countries, try to reach the shores of Spain and Italy by boat each year.
On Wednesday, a 10-year-old girl and two adults died when their boat capsized while trying to cross the Mediterranean Sea to Spain.