Some gases are lighter than air. Hydrogen is the lightest of all, and easily manufactured, even at home -- for example by dropping aluminium foil into a solution of sodium hydroxide (highly dangerous because it will spit droplets of hot caustic liquid at you which may blind you permanently if they land in your eyes).
The corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively. It also produces relaxin, a hormone responsible for softening of the pubic symphysis which helps in parturition.
Supplemental hormones are sometimes effective in reducing or eliminating the pain of endometriosis. That's because the rise and fall of hormones during the menstrual cycle causes endometrial implants to thicken, break down and bleed. Hormone medication may slow the growth and prevent new implants of endometrial tissue.