What is going on

POGP explains the general mechanism: pregnancy "means your body changes a lot. Sometimes these changes put extra pressure on joints and muscles and can cause you to get musculoskeletal symptoms which could be uncomfortable or even painful." Crucially, it adds that these symptoms are most likely in the third trimester "but, in some cases, they can happen in the first or second trimesters or continue after giving birth."

Its list of the reasons is worth reading in full, because it explains why several unrelated joints hurt at once:

changes in the posture of your spine as your baby grew;
a weaker core as the abdominal muscles stretched;
hormones released to allow joints to become more flexible;
more fluid circulating around the body, putting pressure on joints;
changes in balance;
enlarged breasts due to milk production;
feeding your baby in a poor posture;
lifting, bending and carrying after you have given birth.

The HSE describes the same thing from the patient's side: "After birth, you may feel pain in your joints, bones, muscles, ligaments and tendons. Your shoulder may feel sore because you are changing your body posture for feeding. Your lower back or pelvis may also feel tender."

The joints that complain most

POGP names, beyond lower back and pelvic pain: neck pain and stiffness; thoracic pain and stiffness; shooting pain, pins and needles or numbness into the arms or legs; carpal tunnel syndrome; De Quervain's, which is pain at the base of the thumbs; and hip, knee, ankle and foot pain, stiffness or swelling.

Knees and hips tend to hurt from the combination of ligament laxity, altered gait and the sheer repeated load of getting up and down off the floor. Fingers, wrists and thumbs hurt from the new mechanical job of lifting a growing baby dozens of times a day with the arms held in one particular position.

Feeding posture explains more of this than people expect. Hunching over a baby for six to eight hours a day is an unusual physical demand, and shoulders, neck and upper back respond accordingly.

When it is not just the postnatal period

The NHS joint pain page gives a symptom-to-cause table that is useful here:

Pain and stiffness felt on both sides of your body that is worse after not moving, for example when you wake up — possible cause rheumatoid arthritis.
A warm, swollen joint that is more painful when you move it or press on it — possible cause bursitis.
A hot, swollen joint that is difficult to move, with a high temperature or feeling hot, cold and shivery — possible cause joint infection (septic arthritis).

That last one is urgent. And the HSE separately lists severe muscle and joint pain after birth as a possible sign of sepsis, telling you to contact a GP, midwife or public health nurse immediately.

The NHS says to see a GP if joint pain is stopping you doing normal activities or affecting your sleep; if the pain or swelling is getting worse or keeps coming back; if the pain has not improved after treating it at home for two weeks; or if your joints are stiff for more than 30 minutes after waking up. The NHS also says: "Do not self-diagnose, see a GP if you're worried."

The 30-minute stiffness rule is the most useful single line on this page. Aching that eases as you move about is mechanical. Stiffness that takes longer than half an hour to loosen, especially symmetrically in small joints, is worth a blood test. Some autoimmune conditions first appear or flare in the postnatal period, and thyroid problems can also cause aching — both are simple to check for.

What helps

POGP's practical list:

Avoid heavy lifting, bending and twisting where you can.
When lifting your baby, "keep your back straight, bend your knees and keep the load close to you. Try to squeeze your pelvic floor muscles and pull your tummy muscles in towards your spine as you lift and avoid holding your breath."
Pace yourself through the day, doing things for shorter periods before resting or changing activity.
Keep good posture sitting, standing and walking.
Avoid repetitive actions with arms, hands and wrists, to reduce strain on joints.
"Ensure you have a supportive bra throughout your pregnancy and after you have given birth."
Exercise, but adapted — comfortable for your body, with high-impact activity such as running or jumping reconsidered while joints are still loaded.

Two additions that are specific to this stage. First, set up the feeding chair properly — the baby comes up to you, not you down to the baby. Second, stop carrying the car seat on one arm; it is the single most reliable way to keep one shoulder and one wrist angry.

The red flags that mean A&E

POGP says to call your GP straight away or go to your nearest A&E if you have pain going down both legs at the same time, numbness in both legs at the same time, difficulty passing urine, leakage of stool you could not control, numbness around the vagina or back passage, dizziness, double vision or blackouts, numbness in both arms at the same time, unusual severe and persistent headaches, legs giving way for no reason, or changes in speech or swallowing.

Getting seen

The HSE says to talk to a GP if aches and pains continue for more than two months, noting this "may be unrelated to your pregnancy." POGP says to ask for referral to a specialist women's health physiotherapist, and NICE NG194 names physiotherapy as one of the services a GP may refer to from the postnatal check. Say which joints, how long, and what makes it worse. Nobody expects you to have diagnosed it.

Joint Pain After Birth