Ever wonder which states are contributing the most to our ever-expanding population? Or the ones that are contributing the least? Of course, generally, a state’s population size matters most — the larger the size of the populace the more the state is likely to contribute to U.S. population growth. But a state’s fertility rate and the number of women who are within the fertile age range are essential to understanding how states compare.

24/7 Wall St. reviewed the 2015 fertility rate in each state. South Dakota and Utah top the list, with South Dakota just inching past Utah as the state with the highest fertility rate or 77 births per 1,000 women age 15 to 44. Of course, California — the most populous — tops the list of most babies born although its fertility rate is 14th smallest.

48. Massachusetts
> Births per 1,000 women 15-44 yrs.: 52.0
> Births in 2015: 71,492 (19th highest)
> Women aged 15-44: 1,374,336 (14th highest)
> Pop. under 5 years old: 5.4% (tied–6th lowest)
> Poverty rate: 11.5% (tied–13th lowest)

Women in New Hampshire have the fewest babies. With a fertility rate of 51 per 1,000 women within fertile age range — the lowest of all states — births in the state accounted for only 0.3% of the near 4 million births in the United States.

Read on to find out which of the 50 states has the highest fertility rate. Any guesses?

Click here to see the states where people are having the most babies.
Click here to see our detailed findings and methodology.