Chorevia

Day 249 of 280 · 35 weeks + 4 days

The penicillin question

Last reviewed · 3 min read · 8 sources · Plain-text version

Thirty-five weeks and four days. If you've ever been told you're allergic to penicillin, today is the day to ask whether that's still true, before labor.

Size this week
about the size of a honeydew melon
Length this week
around 46.2 cm from head to heel
A woman with a full bump in a denim shirt sitting at a dining table with an old folder of medical papers open, phone to her ear, taking notes, bright afternoon light.

Thirty-five weeks and four days. A question that sounds like paperwork and matters more than it looks: does your chart say you're allergic to penicillin, and is it right?

Your baby

A single honeydew melon on a plain pale wooden table, soft window light.

Around now your baby is around 46.2cm long from head to heel, about the size of a honeydew melon (NHS). MedlinePlus puts their weight at weeks 35 to 37 at about 5 1/2 pounds (2.5 kilograms) (MedlinePlus). Every week from here is mostly about filling out.

Your body

If your group B strep (GBS) swab comes back positive, you'll get antibiotics through an IV during labor (MedlinePlus). The AAP says they work best when given at least 4 hours before delivery, and that antibiotics taken before labor don't prevent passing GBS to the baby (AAP). So the timing is labor itself, and the plan needs to be ready before then.

That's where allergies come in. Roughly nine in ten women who think they are allergic to penicillin are not truly allergic, the AAP says, and it recommends allergy testing (AAP). Finding out now, rather than in labor, gives your team the full picture while there's still time to act on it.

Try today

  1. The penicillin-allergy check

    Time: 15 minutes

    1. Look at what your records say about penicillin, and write down what you remember: what happened, how old you were, who said it was an allergy.

    2. If you think you're allergic, ask your provider this week whether testing makes sense for you, as the AAP recommends (AAP).

    3. Ask what your team would give in labor if you test GBS positive and the allergy stands.

    4. Write the answer on the same page as your GBS swab date, so it's all in one place.

    Make it work:

    No allergy history? Then this one's done in a minute. Use the time to check your swab date is booked.

Watch for

  • Normal

    feeling completely well if you carry GBS; most carriers have no symptoms (AAP).

    Call your provider right away

    if your waters break, and tell them the time and the color or smell (OWH); 18 or more hours after the waters break without delivery raises the chance of passing GBS (MedlinePlus).

  • Normal

    feeling hot, which the NHS lists for these weeks (NHS).

    Call your provider

    for a fever of 100.4°F (38°C) or higher (CDC); a fever in labor is another GBS risk factor (MedlinePlus).

  • Normal

    getting short of breath more easily in the third trimester (OWH).

    Call 911

    for trouble breathing, chest pain, or a fast-beating heart; the CDC lists each as an urgent warning sign (CDC).

For you

There is no vaccine to protect women and babies from GBS (MedlinePlus), and every pregnancy needs its own test, whatever your last result was (AAP). If you test positive, you can still breastfeed (AAP).

If you're the partner: know whether she has a penicillin allergy on file and what the plan is. In labor, you may be the one answering the question.

Sources

This guide is general education that summarizes published research and guidance from groups like the American Academy of Pediatrics, the CDC, and the WHO. It isn’t medical advice, and every child develops on their own timeline. Your pediatrician knows your child; if something feels wrong, call them. In an emergency, call 911.

Get each day’s note the morning it applies

Add your due date to a free Chorevia household, and every morning until the birth the day's note arrives in the app and by email: what's forming, what your body is doing, one thing to try, what to watch for, and a word for you.

Create your household