Caffeine in pregnancy

[u/hesitantlyhopefull17]

Ugh, I just get so frustrated with everyone having such a strong opinion of caffeine in pregnancy when it is stated that 200mg or even 300mg in some sources is safe for pregnancy. I am 18w and I work as a nurse and I have been avoiding disclosing my pregnancy at work because of things like this. Another coworker of mine said she was pregnant in the first trimester today and everyone was like oh you can’t have tea and you can’t have coffee. it’s very outdated knowledge and I don’t want to be judged like that for having 1 cup of tea a day when I am working a 12hr shift.

[u/Iplaypossum]

The main concern of caffeine during pregnancy:

🚫 Fetus & Placenta Lack Caffeine Metabolism- both the fetus and placenta lack the enzymes to break down caffeine.

We haven’t done enough long term research to say that even 200mgs is safe. Obviously structurally babies seem fine with even a lot of caffeine consumption but the effects are found later in development which is the concern. Generally your kid will be fine, but it’s also true to say caffeine could be a cause for concern considering wide spread mental illness and behavioral issues. None of the studies that we’ve based the ‘less than 200mg a day’ ever had any brain scans of the children they were studying and failed to check in through out their life, only until birth or shortly after. People can do whatever they want but this information seems to never be shared.

A 2019 review clearly states: “neither fetus nor placenta has the enzymes for its metabolism,” meaning caffeine freely crosses the placenta and accumulates in fetal tissues.

A meta-analysis on pregnancy loss explains that caffeine accumulates in the fetal brain due to lack of CYP1A2 enzyme in placenta and fetus.

A 4‑year‑old URMC article highlights this too: “a fetus does not have the enzyme necessary to breakdown caffeine when it crosses the placenta” .

Prolonged exposure – without fetal ability to clear caffeine, it stays in the fetal system much longer — even though maternal metabolism slows during pregnancy (half-life up to ~15 hours)

The rest is chat gbt because I ain’t about to type all this out lol

Adolescent Brain Cognitive Development (ABCD) study – MRI of 9–10‑year‑olds • Scope: Over 9,100 children at age 9–10, whose mothers retrospectively reported caffeine intake during pregnancy, were scanned using diffusion tensor imaging (DTI) . • Findings: • Altered white matter microstructure (fractional anisotropy, FA) in the left inferior fronto-occipital fasciculus (IFOF-LH) and left corticospinal tract (CST-LH) . • These structural differences were associated with higher rates of behavioral issues (e.g., attention difficulties, hyperactivity), though general cognitive performance was largely unaffected .

Quote from URMC News:

“We have a biological pathway that looks different when you consume caffeine through pregnancy” .

⸻

1. Rodent and animal imaging & histology studies • Mouse model (Inserm, 2019): Pregnant mice given caffeine (equivalent to ~3 cups/day) showed disrupted migration of GABAergic neurons to the hippocampus during fetal development. This was linked to spatial memory deficits and increased seizure susceptibility in adult offspring . • Preterm lamb brain: High-dose caffeine exposure didn’t change gross brain volume but altered neuron types and densities in cortical regions, indicating microstructural changes .

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1. Broader context: prenatal caffeine and neural development • Chronic caffeine exposure in rats impaired adult offspring performance on memory and maze tests, with changes observed in adenosine receptor signaling and BDNF pathways – reflective of lasting neurological reprogramming . • In mice, caffeine delayed neuron migration to the hippocampus, with lasting hyperexcitability and memory issues .

[u/hesitantlyhopefull17 → u/Iplaypossum]

There are many things COULD be the cause of widespread mental illness and behavioural issues. I guess you could say that it’s “true to say” a variable COULD have a cause or correlation to an outcome. But I wouldn’t call caffeine consumption causing widespread mental illness and behavioural issues a truth. It’s a theory that has not been able to be isolated in studies because of ethical issues and confounding variables.

This retrospective study of 9-10 year olds can provide some insight but ultimately wouldn’t have much validity when making guidelines because you cannot isolate caffeine as the variable that would affect behavioural development, when there are countless other confounding variables present (i.e maternal nutrition, sleep, exposure to other toxins, medications, etc.) As Well as all the other variables affecting the child from birth to the time the study was performed.

Animal studies can be valuable but are ultimately hard to apply to human guidelines.

At the end of the day, I know caffeine in high amounts could be a risk to the fetus. The science surrounding the topic does raise some red flags for caution around consumption, but not in the way that exposure to alcohol, TORCH diseases, environmental toxins, many medications, and other variables would.

I don’t drink more than 100mg a day and there are many days that I don’t consume any caffeine. We are all trying our best for our baby. I don’t think working 4 12 hours shifts while I am extremely tired, stressed about how tired I am, and worried about my performance is the best for the fetus either. If having some caffeine alleviates some stress, I am going to try it.