35 Weeks Pregnant: The Group B Strep Swab and a Baby Running Out of Room

Your Baby at 35 Weeks: Development & Growth

At 35 weeks pregnant, your baby is filling out and has less space to move. Mayo Clinic says "your baby fills most of the space in the amniotic sac and has less room to move," but adds that you will "probably still feel lots of stretches, rolls and wiggles." Mayo Clinic does not give a measurement at week 35 — at week 34 it puts the baby at about 300 millimetres crown to rump and more than 2,100 grams.

Your baby is running out of room this week. Mayo Clinic puts it plainly: at 35 weeks "your baby fills most of the space in the amniotic sac and has less room to move." The big, sweeping turns of earlier weeks give way to tighter, firmer nudges.

That does not mean quiet. Mayo Clinic is clear that you will "probably still feel lots of stretches, rolls and wiggles." The character of the movement changes — the frequency should not.

Mayo Clinic does not restate a size at week 35. The nearest figure is week 34, where Mayo Clinic describes the baby as "nearly 12 inches (300 millimeters) long from crown to rump" and weighing "more than 4 1/2 pounds (2,100 grams)." Length is still measured crown to rump at this stage.

Weight is the headline from here. Mayo Clinic's next figure comes at week 38, "about 6 1/2 pounds (2,900 grams)" — so your baby is somewhere in that climb this week, packing on the fat that will keep them warm after birth.

Your Body at 35 Weeks: Symptoms & Changes

At 35 weeks pregnant, the third trimester is doing real work on your body — a heavy bump, familiar aches, and the practical run-up to birth. SOGC lists tender breasts, constipation, backaches, headaches, mood swings and leg cramps among the common discomforts. This is also the usual window for the Group B Strep swab, and movement awareness stays part of every day. Every pregnancy is different.

The Group B Strep swab is the appointment many mothers have around now. SOGC explains that "screening for Group B Streptococcus is a common and routine part of pregnancy," and that "you will usually be screened for GBS between 35 and 37 weeks of gestation." It is a standard step, not a sign anything is wrong.

Here is what the test actually is. SOGC describes Group B Strep as "a common bacteria which is often found in the vagina, rectum, or bladder," and notes that "women often have GBS without having any symptoms." Carrying it is not an illness. The swab tells your team how to plan.

If it comes back positive, the plan is straightforward. SOGC says "treatment with intravenous (IV) antibiotics is recommended once your labour starts or your water breaks" — timed to labour, not before it — and that this "prevents the bacteria from being passed to your baby during delivery." Your baby is watched a little more closely afterwards: the Canadian Paediatric Society recommends "close in-hospital observation (including vital signs every 3 h to 4 h) for at least 24 h" where antibiotics could not be given in good time. A positive swab changes the logistics of your birth, not the shape of it.

Movement stays central this week, even with less room. SOGC advises being "aware if any changes in your baby's usual activity level, especially in the third trimester," and adds that "your perception of your baby's movements is one of the strongest indicators of your baby's wellbeing." You know your baby's pattern.

Not every tightening is labour. Braxton Hicks are common now — Mayo Clinic describes them as tightness that "vary in strength and length" and "often come and go." They settle if you stop, change position or have a drink. Labour contractions do not settle: SOGC's test is that they "don't go away when you change your activity." You are still before 37 weeks, so regular contractions that keep coming mean a call, not a wait.

Symptoms may still come and go. SOGC lists tender or swollen breasts, constipation, gas and bloating, backaches, headaches, mood swings and leg cramps among the common discomforts of pregnancy. Any of these can be part of your week, and, as SOGC puts it, "every pregnant woman is different."

Headaches are the one to read twice. Most come from the ordinary stuff — a bad night, a tight neck, a late meal. But SOGC names "headaches, blurred vision, dizziness, nausea or vomiting, or shortness of breath" among the symptoms to watch for with preeclampsia, "marked by high blood pressure and the presence of protein in the urine." Severe, unshifting, or arriving with vision changes or sudden swelling — that one gets a phone call.