Table 3.
Data relating to seasonality of autistic births
| Location | Latitude (°N) | Years | Period with highest rate of autistic births, in order | Enhancement ratio (to expeded) | Reference |
| Israel | 32 | 1964–86 | August, March, October | 2.2 (Aug.), 1.6 (Mar) | 67 |
| Japan | 35 | Second quarter | 68 | ||
| USA, North Carolina | 35.5 | March, August | 69 | ||
| USA, New York | 41 | Winter (January, February, March) | 70 | ||
| USA, Boston | 43.3 | March | 8 | ||
| Canada | 45 | Second quarter, third quarter | 71 | ||
| U.K. | 52 | 1947–80 | None found | 72 | |
| Denmark | 52.5 | 1945–80 | March | 7 | |
| Denmark, IQ <35 | 52.5 | 1923–92 | Second quarter | 1.3 | 73 |
| Sweden | 58.5 | 1962–84 | March, January, December | 2.2 (Mar.) | 6 |