Goblins do not have sex. Female goblins lay unfertilized eggs of approximately five to six pounds, 2-3kg, that are oblong, averaging 3 inches, 7cm, at the minor diameter. Unfertilized eggs have a soft, porous exterior and require a dry environment. Hyponatremia by excessive water intake through the shell is a serious and life threatening condition in unfertilized eggs. The female will gestate eggs for about four months before laying, and if the egg is not fertilized within two weeks, median, of laying the embryo loses viability. This is marked by the eggshell turning black and cracking.
Male goblins sit on the eggs and fertilize directly. The male sex organ is a protruding orifice similar to a cloaca that can extend as much as two inches from the pelvis. An opening receives the egg, usually encompassing as much as 10%, and introduces sperm to the eggshell surface. The process takes a few minutes and does not require arousal. A female need not be present.
After fertilization the eggshell hardens within minutes, and becomes nearly air and watertight. A small amount of oxygen and water will pass through the egg, but reports of viable eggs being buried for up to a week and hatching are not uncommon. Temperature regulation is a bigger issue. Goblin eggs are typically nested in insulating matter, and the egg can thermoregulate in environments at the upper end of comfortable to adult goblins. Temperatures about 80 degrees F, 27C, and below 100F, 38C are ideal. Underground, eggs often require additional insulation, and could conceivable hatch in environments below freezing. No major goblin population is known to permanently reside in such places.
Above ground, eggs are laid spring to autumn, though female goblins have great control in timing. Wintertime egg-laying is unknown though not unheard of. Incubation takes about two months. If the shell is cracked or the embryo is removed before hatching, the infant goblin rarely survives. Such premature infant goblins are called wetlings.
If the goblin hatches it is called a shelling. Newborn goblins are developmentally akin to premature human babies. They cannot see, and more dangerously, do not have the breath and lung control to eat and breathe concurrently. Shellings gain this propensity at about six months. Eyes open between eight months and a year. Walking begins at two or three years, about the time the goblin becomes able to eat solid food. A shelling will not need to eat for approximately two to three weeks after hatching.
Adult goblin women do not have pronounced breasts unless lactating. Lactation is initiated by pheromones released in hatching, and exposure to these pheromones induces breast development in all goblins, regardless of biological connection to the shelling. Goblin females who do not want to begin lactating thus avoid nurseries.
Upon exposure to new-hatched shellings, the mammary organs enlarge in size over about two weeks. Nipples grow to four inches, 10cm, or longer. The nipple size allows milk to be administered to the rear of the shellings throat, behind the nostrils. Goblin females nurse for at least a year, and typically begin supplementing with a paste of bread and water for at least another year before weaning the shelling. Small tubes of wood or leather are used for such purposes, leather first, wood second, and allow the infant goblin to consume food while breathing. Asphyxiation during feeding is responsible for more than half of all non-violent infant deaths. In goblin society a rule of thumb is an infant capable of walking to get food is capable of feeding himself.
Goblins thus have significantly easier leadup to parenting. Gestation of unlaid eggs is only mildly inconvenient in the weeks before laying, and often unnoticeable before then. The time between laying and hatching requires little care. After hatching, rearing goblin infants requires time and attention for years until weaning.
Socially, breeding females often establish broods of up to four infants. While twins are possible, multiple concurrent layings are rare enough to be nearly mythological. Additional shellings are thus rarely biologically related. Females share rearing duties, and since exposure to shellings induces lactation without requirement of maternity, the duty is allocated in goblin societies through a number of ways. Some clans, such as Thunderblood use an intricate hierarchy and system of honor and debt. Throathurters are famous for throwing lots.