Sterelisationunable to produce/barren.CAUSES IN WOMEN:STDs mostly syphilis.The bacteria may build up hives along the felopian tube,preventing any passage for fertilisation.VARGINA has natural discharge that lubricates,bacterial action on these discharge releases lactic acidthe acid protects women from germs and any invading bacteriaIf you taste varginal fluids with your tongue,it taste acidic.Whn they stay without bathe,they produce an odour smell.2:HORMONAL IMBALLANCE:Too much progesteron increases milk production but reduces ovulation and s*x drive.Too much estrogen increases ovulation(chances of pregnancy)and high s*x drive.there are medicine to correct this.3:Along term depression or trauma due to worry and stress may lower estrogen level and induce secration of too much adranalin that may lead to intestinal ulcers.4:Early depo(family plnng)in young women or long term use.5:Diseases like;ovarial cystes,H I V etc.*CAUSES IN MEN:1:Failure of cowpas gland to discharge its fluids(clear fluids that drains before ) to nutralise lactic acid not to kill sperms.2:STDs may destroy male organs eg saminal vessicle that must add their fluids into the to become aful compleat spermatozoon.3:Low libido due to stress, worry,fear and other stresses like typhoid ,Tb,malaria and Aids.4:weak sperms due to luck of carbohydrates(ATP)for the mitocondria in spermatozoon;without energy sperms cant swim well to reach the ovum.*FOR MORE INFORMATION and corresponding link,send email to makakiche@gmail.com