Babies conceived 18 months to 5 years after a previous birth are healthier than those conceived at shorter or longer intervals, a massive data analysis shows.
Studies to determine the optimal spacing between a birth and the mother's next pregnancy have yielded mixed results. In an attempt to settle the question, researchers in Colombia analyzed 67 studies that included more than 11 million births worldwide.
Compared with babies conceived 18 to 23 months after a sibling's birth, those conceived within 6 months were 40 percent more likely to be born prematurely, 61 percent more likely to be underweight (less than 2.5 kilograms, or 5.5 pounds), and 26 percent more likely to be small for their gestational age at birth. Babies conceived between 6 and 17 months after their mothers' previous birth also had a slightly increased risk of the three health measures, whereas babies conceived 24 to 59 months after a previous birth had no increased risk.