How Long Are Pigs Pregnant? Gestation, Farrowing Signs and Preparation

If you keep a sow, the first thing to know is when to expect piglets. The second is what to do in the days beforehand. This guide covers both, drawing on published veterinary and industry guidance — and it is general information, not a substitute for your vet.

Gestation: about 115 days

NADIS, the UK's animal disease information service, gives the normal gestation length of a sow or gilt as typically 115 days — three months, three weeks and three days — measured from the first day of service (mating), although a range of 113 to 117 days is quite normal. The Pig Site gives the same figure, with a wider normal range of 111 to 120 days.

Some sources, particularly in the US, quote 114 days. That one-day difference sits inside the range either way, which is why our due-date calculator shows the expected date together with an earliest and a latest date rather than a single day. Treat the expected date as the middle of a window, and begin watching closely from the early end.

The signs that farrowing is close

The Pig Site describes a gradual build-up. Preparation begins about two weeks before, with teat enlargement and more prominent veins in the udder. About four days before, the vulva swells and may redden. About two days before, the mammary glands become taut and more defined, and watery secretions from the teats become more milky within 12 to 24 hours of farrowing. Restlessness and nest-building show that the birth will follow in the next eight to 24 hours.

Preparing a place to farrow

The Pig Site advises that a week or two before the due date it is advisable to give the sow separate accommodation that has been cleaned, disinfected and bedded down. It also advises using shorter or chopped straw for bedding, because newborn piglets are less likely to get caught up in it or bury themselves, which makes them harder for the sow to see. Our bedding guide and the pen size calculator help size the space, and note that Schedule 8 makes a specific exception to the rule that pigs must be able to see other pigs in the week before farrowing and during it (see do pigs need a companion?).

How long farrowing takes, and when to call a vet

The whole birthing process usually takes between three and six hours, with a range of one to ten. NADIS says intervention is needed when delivery arrests with no piglet delivered beyond the normal intervals, or when the sow strains excessively with only small amounts of fluid and no piglet. The Pig Site's rule of thumb is to contact a vet if straining continues unproductively for more than fifteen minutes, or if you see prolonged labour, an exhausted sow or a sow that stops labouring while distressed. Have your vet's number to hand before the due date, not during it.

Before you breed

Breeding is a big commitment: a litter multiplies space, feed and registration obligations, and the legal requirements apply to every pig you hold. Work through plan my setup for the number you would have after farrowing, not just the sow alone.

Sources: NADIS, “Farrowing process”; The Pig Site, “Small-scale pig keeping: the fundamentals of farrowing”. Sources checked: September 2026. General information, not veterinary advice.

Common questions

How long is a pig pregnant?

About 115 days — three months, three weeks and three days — counted from the first day of mating. The normal range is roughly 111 to 120 days, and NADIS describes 113 to 117 as quite normal.

What are the signs a sow is about to farrow?

Teat enlargement and prominent udder veins start about two weeks before. The vulva swells and may redden about four days before, the mammary glands tighten about two days before, and restlessness and nest-building show that farrowing is likely within the next eight to 24 hours.

How long does farrowing take?

The whole birthing process usually takes three to six hours, with a range of one to ten hours.

When should I call a vet during farrowing?

If the sow strains unproductively for more than fifteen minutes with no piglet delivered, or shows prolonged labour, exhaustion or distress, contact a vet straight away.