A small chance of manly gravidity is caused by hormonal problems. The hypothalamus-pituitary endocrine system regulates the chain of hormonal events that enables testes to produce and effectively circulate sperm. Several effects can go wrong with the hypothalamus-pituitary endocrine system
1) The brain can fail to release gonadotrophic-releasing hormone (GnRH) duly. GnRH stimulates the hormonal pathway that causes testosterone conflation and sperm product. A dislocation in GnRH release leads to a lack of testosterone and a conclusion in sperm product.
2) The pituitary can fail to produce enough luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to stimulate the testes and testosterone/ sperm product. LH and FSH are interceders in the hormonal pathway responsible for testosterone and sperm production.
3) The testes Leydig cells may not produce testosterone in response to LH stimulation.
4) A joker may produce other hormones and chemical composites which intrude with the coitus-hormone balance.