Colostrum, allergy meds, and cannabis

Welcome to the weekly ZIP - your Zenith Informed Pregnancy!

Read on for a quick zip through 3 of the week’s most popular pregnancy questions, and the evidence behind them. Plus - bonus content on the latest & greatest in the world of pregnancy research. 

This week's top pregnancy questions:

1️⃣ Can I use BioFreeze or IcyHot?

2️⃣ How soon should I expect colostrum to come in? What should I do when it does?

3️⃣ What allergy meds are safe for pregnancy?

Can I use BioFreeze or IcyHot?

Topical pain relief has been trending, and both BioFreeze and IcyHot come up as hopeful options for moms wanting to avoid oral medications during pregnancy. You might be surprised by the active ingredients and how they differ in safety profile, so here’s the breakdown from the data.

📚The tl;dr from the evidence:  Topical pain relievers are generally considered lower risk than oral pain medications, because much less of the drug is absorbed into the bloodstream (and therefore less likely to potentially reach the placenta and the baby). As with any products with limited direct data in pregnancy, it’s important to look at the active ingredients in the specific product you’re using – topical pain relief typically falls into 3 categories (menthol, methyl salicylate, or topical NSAID).  

Menthol-only options (many versions of Biofreeze) are considered to be the simplest, as there’s low absorption and no signal from animal studies suggesting increased risk of birth defects (though human pregnancy exposure data are limited). 

Products with methyl salicylate (like many IcyHot and similar rub/patch products, sometimes referred to as wintergreen oil) often come with a bit more consideration - this ingredient is closely related to aspirin, which is recommended to be avoided at regular doses as pregnancy progresses due to the potential for fetal kidney damage. While topical use only leads to low absorption, most recommendations suggest avoiding methyl salicylate at/after 20 weeks of pregnancy out of caution. Absorption from topicals can increase when used over a large area or when frequently applied, when there’s a long contact time (e.g. overnight), or in conjunction with heat or tight covering (e.g. a bandage or plastic wrap). 

And finally, topical NSAIDs (like diclofenac) have more established systemic effects and are generally suggested to be avoided, especially as pregnancy progresses. 

👀 Read Penny’s full summary of the evidence for more on topical pain relief

How soon should I expect colostrum to come in? What should I do when it does?

Colostrum comes with tons of questions - what is it? When will it come in? When it comes in, does that mean I’m about to go into labor? Should I be harvesting it before birth? Here’s a little bit more about what the evidence says you can expect. 

📚The tl;dr from the evidence:  Colostrum is the first breastmilk that you produce, and typically shows up in late pregnancy / the first few days postpartum. It’s a thick, yellowish milk that’s particularly rich in immune protection and gut support - it comes in small volumes (so don’t panic if you’re worried about milk volume - a bigger jump in volume usually happens 2-4 days after birth), but is very concentrated in what babies need early on. 

It’s normal to begin producing colostrum during the third trimester (and sometimes even earlier) – some women notice leaking as early as 26-30 weeks, which is considered normal, while others may produce colostrum but not have any leakage (also normal). Leaking colostrum is not a reliable indicator of labor starting soon. 

Some moms consider collecting colostrum in late pregnancy - as an approach to have a “backup supply” ready for the baby right after birth. In low-risk pregnancies, research suggests hand-expressing colostrum at/around 36-37 weeks does not increase risks of preterm birth or NICU admission. However, the evidence is limited for routine use in all pregnancies, so if you’re noticing colostrum come in it’s a good idea to discuss with your doctor whether or not you should express and harvest it (especially if you have increased risk or prior history of preterm labor, or if you’ve already been advised to avoid stimulation).

👀 Read Penny’s full summary of the evidence for more on colostrum

What allergy meds are safe for pregnancy?

From Allegra or Zyrtec to Claritin, Afrin and simply “Which allergy meds can I take right now??”, spring and allergy season is clearly upon us – search volume is surging as moms are trying to find relief for seasonal allergies and symptoms. 

📚The tl;dr from the evidence: Many allergy medications can be used during pregnancy, with a focus on “local” (vs whole body) exposures in options like nasal sprays or eye drops, and non-drowsy antihistamines. Steroid nasal sprays (active ingredients like budesonide, fluticasone, and mometasone, found in products like Rhinocort and Flonase) can be highly effective for a stuffy/runny nose or sneezing, and have reassuring pregnancy safety data at normal doses. Products with other active ingredients, like triamcinolone (Nasacort) or oxymetazoline (Afrin) have less conclusive data - most human data hasn’t shown an increase in birth defects, but there’s not enough research to conclusively say there is zero risk. 

Oral antihistamines are fairly well studied, and generally considered safe - the data does not suggest loratadine (Claritin) and cetirizine (Zyrtec) are likely to increase the chance of birth defects in the baby, including first trimester use. While there aren’t randomized controlled trials (the gold standard for causality!), these antihistamines have longstanding use and robust observational data supporting pregnancy safety. 

The big allergy meds watch-out: decongestants (like phenylephrine or pseudoephedrine, common in medications like Sudafed) have more mixed evidence, so where possible, other options are typically recommended. Some antihistamines do have product options that include phenylephrine or pseudoephedreine, like Claritin-D or Allegra-D, so always check the label on the exact product you’re considering. 

👀 Read Penny’s full summary of the evidence for more on allergy meds

🤓 Zenith's top read of the week

Bonus: what the Zenith team found interesting this week. Think cool pregnancy research or recently published studies, news in pregnancy health and policy, and more!

The Complex Motives behind Cannabis Use in Pregnancy (Ruta Nonacs, MGH Center for Women’s Mental Health) - Cannabis use during pregnancy is becoming more common, but it’s complex both to study and to support effectively.

This new research looked at nationally collected survey data from over 800,000 moms in 10 states, to try and understand the most common reasons for use. They found that reported use (in nearly 4% of the pregnancies studied) was primarily for mental health symptom management, followed by management of nausea/vomiting and pain (aka… pregnancy symptoms). 

In an ideal world, moms can be supported and screened prior to pregnancy so that they can find effective alternatives to cannabis use, which based on the limited data we do have – can be associated with sub-optimal pregnancy outcomes like preterm birth, low birth weight, and potentially neurodevelopmental concerns for the child. Studies like this are a great step in the right direction of understanding use patterns, to more effectively support women with tapering off before pregnancy and finding effective alternatives suited to their primary concerns. 

Key excerpt:

“The most common motivations for prenatal cannabis use were: Mental health symptoms (82.81%), Relief of gastrointestinal symptoms (77.10%), Pain relief (48.67%), Fun or relaxation (40.18%) and Management of chronic condition–related symptoms (26.31%).

Most participants (84.32%) reported two or more reasons for use. Women citing multiple motivations were more likely to report daily use compared with those reporting only one reason (86.96% vs. 10.40%).”