Camilla Haavaldsen

Placental weight in singleton pregnancies with and without assisted reproductive technology: a population study of 536 567 pregnancies

BACKGROUND Pregnancies conceived by assisted reproductive technology (ART) are at increased risk of adverse outcomes. Previous studies have suggested increased placental weight and increased placental weight/birthweight ratio in pregnancies associated with adverse outcomes. We therefore studied the association of ART with placental weight and placental weight/birthweight ratio. METHODS We included all singleton births in the Medical Birth Registry of Norway during the period 1999-2008 (n = 536 567, including 8259 after ART). We divided placental weight and placental weight/birthweight ratio into quartiles, and calculated the proportions of ART and spontaneous pregnancies in the lowest and the highest quartile by length of gestation. Thereafter, we estimated crude and adjusted odds ratios (ORs) for being in each quartile of placental weight for ART pregnancies with spontaneous pregnancies as the reference. The analyses were repeated with ART pregnancies subgrouped into IVF or ICSI. RESULTS Mean placental weight was 678.9 g in pregnancies conceived by ART, and 673.0 g in pregnancies after spontaneous conception. ART pregnancies were overrepresented in the highest quartile of placental weight and underrepresented in the highest quartile of birthweight, independent of length of gestation at delivery. Thus, placental weight/birthweight ratio was higher in ART pregnancies. For ART pregnancies, the OR for being in the highest quartile of placental weight was 1.37 (95% confidence interval 1.30-1.45) after adjustment for length of gestation, offspring birthweight, parity, fetal sex, maternal age, pre-eclampsia and diabetes. There was no difference in placental weight/birthweight ratio between IVF and ICSI pregnancies. CONCLUSIONS We found larger placentas and a higher placental weight/birthweight ratio among pregnancies conceived by ART compared with spontaneous pregnancies, and the difference was independent of length of gestation at delivery and ART method.

The association of maternal age with placental weight: a population‐based study of 536 954 pregnancies

Please cite this paper as: Haavaldsen C, Samuelsen S, Eskild A. The association of maternal age with placental weight: a population‐based study of 536 954 pregnancies. BJOG 2011;118:1470–1476.

Fetal death and placental weight/birthweight ratio: a population study.

To study the association of placental weight and placental weight/birthweight ratio with gestational age‐specific fetal death.

Recurrence of hypertensive disorders of pregnancy: an individual patient data metaanalysis.

OBJECTIVE We performed an individual participant data (IPD) metaanalysis to calculate the recurrence risk of hypertensive disorders of pregnancy (HDP) and recurrence of individual hypertensive syndromes. STUDY DESIGN We performed an electronic literature search for cohort studies that reported on women experiencing HDP and who had a subsequent pregnancy. The principal investigators were contacted and informed of our study; we requested their original study data. The data were merged to form one combined database. The results will be presented as percentages with 95% confidence interval (CI) and odds ratios with 95% CI. RESULTS Of 94 eligible cohort studies, we obtained IPD of 22 studies, including a total of 99,415 women. Pooled data of 64 studies that used published data (IPD where available) showed a recurrence rate of 18.1% (n=152,213; 95% CI, 17.9-18.3%). In the 22 studies that are included in our IPD, the recurrence rate of a HDP was 20.7% (95% CI, 20.4-20.9%). Recurrence manifested as preeclampsia in 13.8% of the studies (95% CI,13.6-14.1%), gestational hypertension in 8.6% of the studies (95% CI, 8.4-8.8%) and hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome in 0.2% of the studies (95% CI, 0.16-0.25%). The delivery of a small-for-gestational-age child accompanied the recurrent HDP in 3.4% of the studies (95% CI, 3.2-3.6%). Concomitant HELLP syndrome or delivery of a small-for-gestational-age child increased the risk of recurrence of HDP. Recurrence increased with decreasing gestational age at delivery in the index pregnancy. If the HDP recurred, in general it was milder, regarding maximum diastolic blood pressure, proteinuria, the use of oral antihypertensive and anticonvulsive medication, the delivery of a small-for-gestational-age child, premature delivery, and perinatal death. Normotensive women experienced chronic hypertension after pregnancy more often after experiencing recurrence (odds ratio, 3.7; 95% CI, 2.3-6.1). CONCLUSION Among women that experience hypertension in pregnancy, the recurrence rate in a next pregnancy is relatively low, and the course of disease is milder for most women with recurrent disease. These reassuring data should be used for shared decision-making in women who consider a new pregnancy after a pregnancy that was complicated by hypertension.

The impact of maternal age on fetal death: does length of gestation matter?

OBJECTIVE The objective of the investigation was to study the association of fetal death with maternal age by length of gestation. STUDY DESIGN This was a population study including all ongoing pregnancies after 16 weeks of gestation in Norway during the period 1967-2006 (n = 2,182,756). RESULTS The risk of fetal death was 1.4 times higher in women 40-44 years old than in women aged 20-24 years in midpregnancy but 2.8 times higher at term. In term pregnancies the relative importance of maternal age increased by additional pregnancy weeks. In gestational weeks 42-43, the crude risk was 5.1 times higher in mothers 40 years old or older. In the recent period, the elevated risk of fetal death in elderly mothers at term has been attenuated. CONCLUSION Women 40 years old or older had the highest risk of fetal death throughout pregnancy, particularly in term and postterm pregnancies. Improved obstetric care may explain the attenuation of risk associated with age in recent time.

Placental weight relative to birthweight in pregnancies with maternal diabetes mellitus

To study the association of maternal diabetes mellitus with placental weight, birthweight and placental weight‐to‐birthweight ratio.

Association of placental weight with cerebral palsy: population-based cohort study in Norway

To study the risk of cerebral palsy (CP) associated with placental weight, and also with placental weight/birthweight ratio and placental weight/birth length ratio.

Placental weight and placental weight to birthweight ratio in relation to Apgar score at birth: a population study of 522 360 singleton pregnancies.

To study whether placental weight or placental weight to birthweight ratio are associated with Apgar score in the newborn 5 min after birth.

Paternal age, placental weight and placental to birthweight ratio: a population-based study of 590 835 pregnancies

STUDY QUESTION Is the age of the father associated with placental weight or the ratio of placental weight to birthweight? SUMMARY ANSWER Placental weight and placental to birthweight ratio increased according to increasing paternal age, also after adjustment for maternal age. WHAT IS KNOWN ALREADY High paternal age and also high placental to birthweight ratio have been associated with adverse pregnancy outcome. STUDY DESIGN, SIZE AND DURATION We performed a population-based study and included all singleton births after 22 weeks of gestation in the Medical Birth Registry of Norway (n = 590,835) during the years 1999-2009. PARTICIPANTS/MATERIALS, SETTING, METHODS We compared mean placental weight and placental to birthweight ratio between paternal age groups. The association of paternal age with placental weight was estimated by linear regression analyses, and adjustments were made for maternal age, birthweight, parity, offspring sex, gestational age at birth, maternal smoking, pre-eclampsia, maternal diabetes mellitus and pregnancy after assisted reproductive technology (ART). MAIN RESULTS AND THE ROLE OF CHANCE In pregnancies with fathers aged 20-24 years old, the mean placental weight was 656.2 g [standard deviation (SD) 142.8], whereas it was 677.8 g (SD 160.0) in pregnancies with fathers aged 50 years or older (P < 0.001). The mean offspring birthweight in pregnancies with fathers aged 20-24 year old was 3465.0 g (SD 583.8), and it was 3498.9 g (SD 621.8) when the father was 50 years or older (P < 0.001). The placental to birthweight ratio in the corresponding paternal age groups were 0.191 (SD 0.039) and 0.196 (SD 0.044) (P < 0.001). In multivariable linear regression analysis the placentas in pregnancies fathered by a man of 50 years or older were estimated to weigh 13.99 g [95% confidence interval (CI) 10.88-17.10] more than in pregnancies with a 20-24-year-old father (P < 0.001) after adjustment for maternal age, birthweight, parity, offspring sex, gestational age at birth, maternal smoking, pre-eclampsia, maternal diabetes mellitus and pregnancy after ART. LIMITATIONS, REASONS FOR CAUTION Paternal age explains only a small proportion of the total variation in placental weight. WIDER IMPLICATIONS OF THE FINDINGS Our findings may increase the understanding of the fathers role in human pregnancy. STUDY FUNDING/ COMPETING INTEREST(S) Norwegian Resource Centre for Womens Health, Norway. No conflict of interest. TRIAL REGISTRATION NUMBER N/A.

Maternal age and serum concentration of human chorionic gonadotropin in early pregnancy

To study whether maternal age is associated with serum concentration of human chorionic gonadotropin in early pregnancy.