BP dip in 2nd trimester

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Re : BP dip in 2nd trimester

Postby akemt » Thu Dec 18, 2003 09:11 pm


I don't have a good section to quote in particular, but Chesley's Hypertensive Disorders in Pregnancy, Second Edition talks about a decrease in pressures around 16-20 weeks. It is a bunch of medical jargon, but I'll give you a quote. It has some great graphs, but I don't have a scanner and don't even know if that's legal??? lol The graphs start at about 14 wks gestation and show a decrease from there with the lowest point being around 16-24 weeks with blood pressures increasing gradually toward the end of pregnancy and passing the 14 week pressures. The ammount of change is small in my opinion (averaging a decrease of less than 10 by the graph) and so may not be easily noticed unless you are keeping close track of your Blood pressures.

Here's a quote: "In general, mean arterial pressure declines in the first trimester, reaching a nadir between 16-20 weeks' gestation with a return to control values near term. Diastolic pressures decline to a greater extent than systolic pressures, the average mean change being about 10 mm Hg." (Lindheimer, Roberts, Cunningham, pg. 70)

Sorry, trying my best to pretend I have some knowledge of how to site a work, but I honestly don't remember! lol

Catherine (22)
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Emma Margaret (03/02/03) 37 weeks from PIH & oligo

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Re : BP dip in 2nd trimester

Postby catherine » Thu Dec 18, 2003 08:23 pm

It's because of two things, first the increase in blood volume that comes from having to supply the growing baby as well as yourself and second because hormones relax the blood vessel walls to enable them to carry all that extra fluid. It's a second trimester phenomenon because that is when the baby really starts to grow and the volume expansion keeps pace with that.

At least that is my understanding. I think that the dip can be quite subtle and may barely be noticed. Certainly in my preeclampsia pregnancy my bp never went higher than 130/80 for the whole time (with one exception a 140/80 at the end of a horribly stressful day and bad appointment) but it didn't drop either. I never really paid too much attention. I'm normally in the 110-120/70-80 range anyway and so didn't think that those numbers counted as elevated. I was being seen by a peri (pure coincidence not known to be high risk) for the whole pregnancy and she never freaked about those numbers. Last time around when I was much more vigilant I did see a very slight dip but still sitting in same 110-120/70-80. I think that so long as your bp stays in the normal range and there is no proteinuria then there is no obvious reason for concern (unless you normally have an obscenely low bp).

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Re : BP dip in 2nd trimester

Postby kim » Thu Dec 18, 2003 07:26 pm

I have heard it from many docs, (mine included) that bp dips in the 2nd trimester... Although I'm not sure why, exactly...

Kim Schwintz
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Ainsley Kathryn 11/26/02-36 Weeks Preeclampsia

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