Is there a natural hike in BP in the 3rd trimester?

[danielsmom]

I know that BP tends to lower in the 2nd tri. Does it elevate a little in the 3rd trimester typically for healthy pregnancies? My systolic is running about +5 and diastolic about +10 this week. It's still well within normal, but I was curious since it has been consistent. I'm 33 weeks.

[JB]

My OB and my nephrologist both told me there is an increase in blood pressure in the third trimester, but didn't tell me how much I should expect. +10 for diastolic sounds like a lot, but I really don't know how much increase is considered normal. I would definitely ask my doctor about it, but I ask about everything now because last time I brushed stuff off as normal pregnancy symptoms and they actually weren't (headaches, swelling feet, heartburn, etc.).

I am also 33 weeks (due June 19th, c-section scheduled for the 14th), but my blood pressure has actually dropped slightly. I think in my case it is due to the fact that I had to go on the gestational diabetes diet (I have read some studies that show a reduced sugar intake can also reduce blood pressure by a couple of points.. at any rate, I'm eating a lot fewer processed foods) and stopped eating out almost entirely a few weeks ago (we were eating out too much and I was getting way more sodium than was good for me).

[danielsmom]

Thanks JB, we'll talk about it Friday at my next appt. It's still nice and low, 110/70, but I used to consistently get 100+/60+. I was in a LOT of pain this weekend, and probably some stress from it, so that could be part of it. I got a painful hemorrhoid and UTI the same day... I guess hemorrhoids are common in late pregnancy. I've never had one in my life and look forward to never experiencing that again. Thankfully, the meds are working.

So are you ready for this? I'm scheduled for June 5th, at 38w3d, less than 5 weeks away. This nesting thing is wearing me out, but I can't wait.

[MomTimesThree]

Thanks for asking this question. As we gear up to hit the 3rd trimester (all fingers crossed- we're 27 weeks and some change) I've noticed a bit of a rise and wondered if it was a natural part of all those lovely pregnancy changes.

[lemons]

The short answer is "Yes".

There is an article (JASH. 2008;2(6):484-494) posted under the Care Providers section (http://www.preeclampsia.org/pdf/PIIS193 ... 00185X.pdf) that has a graph (on page 2) showing average BP over the course of pregnancy, showing systolic and diastolic separately. The data are old (from a paper published in 1976) but are still considered to be representative, as far as I can tell. In short, the graph suggests that on average:
BP decreases until hitting a low sometime about 21-22 weeks
BP stays at about this level until about 30 weeks
BP starts on a slow but steady increase from 30 weeks until delivery

I also think, in my non-medical opinion , that the UTI might be causing your BP to run a little higher. I'm sure that you will be talking to your physician about all of this on Friday. Let us know what he/she thinks. I am interested to know.

[JB]

After my c-section last year the nurses urged me to take pain meds because they said pain can elevate your blood pressure and my BP was still really high, so I took them, even though I didn't feel that I needed them that much (I have a pretty high pain tolerance and worry about taking meds that can be addictive). So yeah, I think your blood pressure could definitely be affected by any illness you have that causes you pain. Also, your BP is still really good at those levels!

Don't worry, June 5th will be here before you know it! I keep thinking how strange it will be to have a full-term baby. This pregnancy has been so different from my last that I really have started to believe I'm going to make it to my scheduled date. Because I have gestational diabetes this time my baby is already measuring large (88th percentile), it will be so different from my itty bitty baby I had last time. I'm really looking forward to being able to see him right when he's born and to get to take him home right away.

[danielsmom]

I just got back from the OB. I thought my appt was Friday, but then realized it was today. I'm in no pain now, all is healed, and my BP is back down! It was 110/60 at the doctor's office. So, it could be possible that the pain caused a slight hike. I'm glad I called in for help and got a prescription, instead of toughing it out and hoping it got better and didn't get worse.

Lemons, that was a great article. The chart was especially helpful. So, I guess we can expect a slight rise of 5 points or so in the 3rd tri, but not a significant jump, at least in a healthy pregnancy.

JB - I know! How strange would it be to take a baby home, that isn't itty bitty, and being healthy when you have him/her?! I can't imagine! But it's becoming a more real possibility.

[lemons]

I'm so glad to hear that you are feeling better and that your BP is back to your normal. And I hope that you had nothing but good news at your appointment yesterday!

As for what to consider a "normal" rise in BP in the 3rd Trimester- the graph I mentioned below is clearly from an older paper since it doesn't show some information that is considered mandatory by today's standards, specifically it doesn't show any kind of analysis of standard deviations or other error. It is possible that the error analysis was conveyed in the text of the original 1976 paper. Unfortunately, I don't have access to the original so I don't know for sure. So, why am I telling you this??

The graph shows the average systolic and diastolic BPs of over 6,000 pregnant women over the course of their pregnancies. Since we are looking at all of the women combined, we don't know what the lowest BP was, only what the average was. Nor do we know what the highest BP was. Since we don't know these numbers, we can't get a good idea of what the range of BPs was for the study group. And the range would be much better at helping us decide what is considered "normal". (The error analysis that I mentioned above would help answer these questions by providing some information on the range of BPs). Even better would be to know what the absolute increase in BP was for individuals in the study group (ie Patient A's BP started at 110/65, decreased to a low of 100/60 at 20 weeks, and then increased to 115/68 at delivery). I hope this makes sense.

But yes, I think that the graph suggests that a slow, sustained rise in systolic BP of 5-7 mm Hg from 22 weeks gestation until delivery at 40 weeks should be considered average. But how much further can it rise and still be considered within a "normal" range? This graph doesn't provide that information. BUT, taking into account the old diagnostic criteria for PE (a rise of 30 mm Hg or greater in systolic pressure), my non-medical guess is that a 10-15 mm Hg increase in systolic BP (which should be noted by a physician) is probably within that normal range. I may have to track the original paper down to see if there is any more information... And if anyone else has any input as to what is considered normal, I would love to know.

But hopefully you will not have any more reason to worry about your BP between now and June 5th! Best of luck to you and baby! And let me know if any of this didn't make sense or if you have any other questions.

[danielsmom]

Yeah, that makes sense. I still think the graph was generally helpful. I'm not sure what it would look like if they got more specific and didn't just take averages... normal BP is so individualized, and varies a lot even within the individual. I get swings of a lot more than 5 mm Hg between appointments, but I average generally the same. I do think it's up a tad bit in the 3rd trimester, about the same amount that the chart suggests. So I feel comfortable with that explanation, and knowing I'm still in healthy levels.

I'm more positive since we passed our son's delivery gestation, but I'm also keeping a close eye out for bad turns. This thing can come out of no where and move fast. Any information helps to discern rational fears from the irrational, I guess.

[lemons]

I'm glad that you found the graph useful and that it helped to ease your fears- I don't think any fears during pregnancy are "irrational" after you've had PE once! And I'm glad that you are feeling more positive since passing your son's gestational age at delivery. I can imagine that the weeks/days beforehand were quite stressful I'm keeping my fingers crossed for you and baby!