The vast majority of macaque subfamily get pregnant during a very limited mating season. In high latitudes, mating occurs in autumn; in the tropics, long-tailed monkeys become pregnant during the dry season; and in dry countries, red monkeys become pregnant during the rainy season. Baboons and white-browed monkeys can give birth at any time of the year, but certain ecological pressures, such as prolonged droughts that cause multiple cub deaths, may have an impact on female monkeys who re-conceive at the same time of the following year. In fact, it is the influence of climate on food supply that leads to the seasonality of the breeding season. Mating periods may last for several months (such as long-tailed black-jawed monkeys) or may be concentrated for a few weeks (such as red monkeys and pygmy long-tailed monkeys), and during this annual breeding season, the female monkeys are likely to have only one ovulation. Females usually mate multiple times over several consecutive days, and pregnant females may also mate again. Male rhesus macaques also exhibit seasonal variations, with testosterone levels decreasing during the non-breeding period and correspondingly reducing testicular size.
Because spouses tend to be familiar with each other, and they focus only on signals that they can mate, the courtship process is usually very short. But female red monkeys have a much more complicated courtship: they curl their tails, stick out their chins, pout their lips, bend down and run low; they also puff up their cheeks, hold the vulva in front of one, and sometimes rub it with a branch on the other forefoot. They will court frequently, and a "couple" will spend hours or days together on the edge of the monkey pack intimately. In some species, a single mating process can lead to ejaculation, while in others, several matings can cause the process to occur. Mating mates are often disturbed by juvenile monkeys, especially the offspring of females. They are probably keen on this because they want to postpone the birth of their "younger brother or sister", because their birth will distract the mother. This interference is enough to force the mates to mate multiple times in order for the male to complete the ejaculation.
After a 5 to 6 months gestation, a cub is born (twins are extremely rare). The process of giving birth in monkeys is much shorter than in humans, and female monkeys can give birth anywhere. Newborn monkeys are covered in soft hair, their eyes are open, and they often cling to the mother's hair, even when the quadruples have not fully emerged from the mother's body. Immediately after birth, the cub clings to the mother's abdomen, and usually they can support their weight, but the mother monkey usually supports the cub's back with a forefoot so that she can support the cub for the first few hours while walking. Newborn monkeys often hold nipples in their mouths, even when they are not breastfeeding. Most monkeys are born at night, often on trees where the mother monkeys sleep. After the mother monkey gives birth to the baby monkey, she will eat the placenta and lick the baby baby before the morning comes. The cubs of the red monkeys are usually born on the ground, usually during the day. It seems that the choice of delivery time is related to the pressure from predators, as red monkeys usually sleep in low trees at night, which makes them extremely vulnerable to predators. Although the sounds made by the mother during childbirth hardly attract the attention of the other members of the monkey group, once born, the cub becomes the focus of other adult monkeys in the colony, as well as the young female monkeys, and they may compete to obtain permission from the mother of the cub to gain the right to pet and care for the cub.
As the monkey's ability to walk independently gradually increases, the mother monkey's care behavior towards it will change accordingly. Although breastfeeding becomes less frequent after a few months, breastfeeding generally continues until the next cub is born. For most macaques, long-tailed black-jawed monkeys, red monkeys, and pygmy long-tailed monkeys, breastfeeding may occur about a year after the baby monkey is born, while for long-tailed monkeys living in the forest, such as blue long-tailed monkeys, this behavior can last even two years or more. The interval between baboon deliveries often varies, generally between 15 and 24 months, most likely because of the amount of food available at different times. If the pups are miscarried or die, the interval between births may be shortened, although the variation in the interval between births is not noticeable in seasonally breeding monkeys.