Emerging understanding and measurement of plasma volume expansion in pregnancy

Vricella, Laura K.

doi:10.3945/ajcn.117.155903

“…Most of the studies available for this review were done in the 1960s and 1970s, a period when pregnant women were generally younger and leaner than those today [55][56][57][58][59][60]. It is unclear if the same pattern of expansion would be observed for older pregnant women [61], and maternal age during pregnancy has been continuing to rise in the US [62,63]. Similarly, the prevalence of prepregnancy overweight and obesity has increased dramatically since the 1990s [55,56,58,59].…”

Section: Discussionmentioning

confidence: 99%

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Aguree

¹

,

Gernand²

2019

Preprint

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Background: Plasma volume expansion is an important physiologic change across gestation. High or low expansion has been related to adverse pregnancy outcomes, yet there is a limited understanding of normal/healthy plasma volume expansion. We aimed to evaluate the pattern of plasma volume expansion across healthy pregnancies from longitudinal studies. Methods: We conducted a systematic review and meta-analysis to identify original studies that measured plasma volume in singleton pregnancies of healthy women. Specifically, we included studies that measured plasma volume at least two times across gestation and one time before or after pregnancy in the same women. PubMed, Web of Science, Cochrane, CINAHL, and clinicaltrials.gov databases were searched from the beginning of each database to February 2019. We combined data across studies using a random effects model. Results: Ten observational studies with a total of 347 pregnancies were eligible. Plasma volume increased by 6% (95% CI 3-9) in the first trimester compared to the non-pregnant state. In the second trimester, plasma volume was increased by 18% (95% CI 12-24) in gestational weeks 14-20 and 29% (95% CI 21-36) in weeks 21-27 above the nonpregnant state. In the third trimester, plasma volume was increased by 42% (95% CI 38-46) in weeks 28-34 and 48% (95% CI 44-51) in weeks 35-38. The highest rate of increase occurred in the first half of the second trimester. Included studies were rated from moderate to high quality; 7 out of 10 studies were conducted over 30 years ago. Conclusions: In healthy pregnancies, plasma volume begins to expand in the first trimester, has the steepest rate of increase in the second trimester, and peaks late in the third trimester. The patterns observed from these studies may not reflect the current population, partly due to the changes in BMI over the last several decades. Additional longitudinal studies are needed to better characterize the range of normal plasma volume expansion across maternal characteristics.

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“…Some nutritional status biomarkers like vitamin B6, folate, zinc, copper, and hemoglobin have all been shown to change across gestation; the role of plasma volume in these changes has not been well described except for hemoglobin (creating lower cutoffs to diagnose anemia in pregnancy) [17,54] Most of the studies available for this review were done in the 1960s and 1970s, a period when pregnant women were generally younger and leaner than those today [55][56][57][58][59][60]. It is unclear if the same pattern of expansion would be observed for older pregnant women [61], and maternal age during pregnancy has been continuing to rise in the US [62,63]. Similarly, the prevalence of prepregnancy overweight and obesity has increased dramatically since the 1990s [55,56,58,59].…”

Section: Discussionmentioning

confidence: 99%

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Aguree

¹

,

Gernand²

2019

Preprint

View full text Add to dashboard Cite

Background: Plasma volume expansion is an important physiologic change across gestation. High or low expansion has been related to adverse pregnancy outcomes, yet there is a limited understanding of normal/healthy plasma volume expansion. We aimed to evaluate the pattern of plasma volume expansion across healthy pregnancies from longitudinal studies. Methods: We conducted a systematic review and meta-analysis to identify original studies that measured plasma volume in singleton pregnancies of healthy women. Specifically, we included studies that measured plasma volume at least two times across gestation and one time before or after pregnancy in the same women. PubMed, Web of Science, Cochrane, CINAHL, and clinicaltrials.gov databases were searched from the beginning of each database to February 2019. We combined data across studies using a random effects model. Results: Ten observational studies with a total of 347 pregnancies were eligible. Plasma volume increased by 6% (95% CI 3-9) in the first trimester compared to the non-pregnant state. In the second trimester, plasma volume was increased by 18% (95% CI 12-24) in gestational weeks 14-20 and 29% (95% CI 21-36) in weeks 21-27 above the nonpregnant state. In the third trimester, plasma volume was increased by 42% (95% CI 38-46) in weeks 28-34 and 48% (95% CI 44-51) in weeks 35-38. The highest rate of increase occurred in the first half of the second trimester. Included studies were rated from moderate to high quality; 7 out of 10 studies were conducted over 30 years ago. Conclusions: In healthy pregnancies, plasma volume begins to expand in the first trimester, has the steepest rate of increase in the second trimester, and peaks late in the third trimester. The patterns observed from these studies may not reflect the current population, partly due to the changes in BMI over the last several decades. Additional longitudinal studies are needed to better characterize the range of normal plasma volume expansion across maternal characteristics.

show abstract

“…Most of the studies available for this review were done in the 1960s and 1970s, a period when pregnant women were generally younger and leaner than those today [55][56][57][58][59][60]. It is unclear if the same pattern of expansion would be observed for older pregnant women [61], and maternal age during pregnancy has been continuing to rise in the US [62,63]. Similarly, the prevalence of prepregnancy overweight and obesity has increased dramatically since the 1990s [55,56,58,59].…”

Section: Discussionmentioning

confidence: 99%

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Aguree

¹

,

Gernand²

2019

Preprint

View full text Add to dashboard Cite

Background: Plasma volume expansion is an important physiologic change across gestation. High or low expansion has been related to adverse pregnancy outcomes, yet there is a limited understanding of normal/healthy plasma volume expansion. We aimed to evaluate the pattern of plasma volume expansion across healthy pregnancies from longitudinal studies. Methods: We conducted a systematic review and meta-analysis to identify original studies that measured plasma volume in singleton pregnancies of healthy women. Specifically, we included studies that measured plasma volume at least two times across gestation and one time before or after pregnancy in the same women. PubMed, Web of Science, Cochrane, CINAHL, and clinicaltrials.gov databases were searched from the beginning of each database to February 2019. We combined data across studies using a random effects model. Results: Ten observational studies with a total of 347 pregnancies were eligible. Plasma volume increased by 6% (95% CI 3-9) in the first trimester compared to the non-pregnant state. In the second trimester, plasma volume was increased by 18% (95% CI 12-24) in gestational weeks 14-20 and 29% (95% CI 21-36) in weeks 21-27 above the nonpregnant state. In the third trimester, plasma volume was increased by 42% (95% CI 38-46) in weeks 28-34 and 48% (95% CI 44-51) in weeks 35-38. The highest rate of increase occurred in the first half of the second trimester. Included studies were rated from moderate to high quality; 7 out of 10 studies were conducted over 30 years ago. Conclusions: In healthy pregnancies, plasma volume begins to expand in the first trimester, has the steepest rate of increase in the second trimester, and peaks late in the third trimester. The patterns observed from these studies may not reflect the current population, partly due to the changes in BMI over the last several decades. Additional longitudinal studies are needed to better characterize the range of normal plasma volume expansion across maternal characteristics.

show abstract

Emerging understanding and measurement of plasma volume expansion in pregnancy

Cited by 67 publications

References 41 publications

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

Plasma volume expansion across healthy pregnancy: a systematic review and meta-analysis of longitudinal studies

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