方法
Dr. Landrum Shettles proposed that Y-sperm (male) are faster but shorter-lived, while X-sperm (female) are slower but more resilient.
- 男の子: 排卵日直前。
- 女の子: 2-4日前。
シェトルズ法。
Dr. Landrum Shettles proposed that Y-sperm (male) are faster but shorter-lived, while X-sperm (female) are slower but more resilient.