Answer:
Extremely preterm infant.
Explanation:
The gestation period of the human is nine months. The offspring grows and fully developed in this period. After the completion of gestation period, the parturition period starts.
Sarah and his husband has lost their baby at 27 week of conception. The infant is extremely week at this period and admitted to the intensive care unit. The baby is in the extreme preterm infant as he has not completed its nine months development period.
Thus, the answer is extremely preterm infant.