Trends in perinatal health after assisted reproduction: a Nordic study from the CoNARTaS group

The health outcomes of human offspring conceived by assisted reproductive technologies (ART)

Concerns have been raised about the health and development of children conceived by assisted reproductive technologies (ART) since 1978. Controversially, ART has been linked with adverse obstetric and perinatal outcomes, an increased risk of birth defects, cancers, and growth and development disorders. Emerging evidence suggests that ART treatment may also predispose individuals to an increased risk of chronic ageing related diseases such as obesity, type 2 diabetes and cardiovascular disease. This review will summarize the available evidence on the short-term and long-term health outcomes of ART singletons, as multiple pregnancies after multiple embryos transfer, are associated with low birth weight and preterm delivery, which can separately increase risk of adverse postnatal outcomes, and impact long-term health. We will also examine the potential factors that may contribute to these health risks, and discuss underlying mechanisms, including epigenetic changes that may occur during the preimplantation period and reprogram development in utero, and adult health, later in life. Lastly, this review will consider the future directions with the view to optimize the long-term health of ART children.

Cardiovascular and metabolic profiles of offspring conceived by assisted reproductive technologies: a systematic review and meta-analysis

OBJECTIVE

To evaluate cardiovascular and metabolic features of offspring conceived by in vitro fertilization/intracytoplasmic sperm injection (IVF-ICSI).

DESIGN

Literature review and meta-analysis.

SETTING

Not applicable.

PATIENT(S)

Offspring from IVF-ICSI versus natural conception.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Systolic and diastolic blood pressure (SBP and DBP), cardiovascular function, body mass index (BMI), and lipid and glucose profiles.

RESULT(S)

We included 19 studies that had recruited 2,112 IVF-ICSI and 4,096 naturally conceived offspring, ranging from childhood to early adulthood. The blood pressure levels of IVF-ICSI offspring were statistically significantly higher than those of naturally conceived offspring (weighted mean differences and confidence intervals: 1.88 mm Hg [95% CI, 0.27, 3.49] for SBP and 1.51 mm Hg [95% CI, 0.33, 2.70] for DBP). In addition, cardiac diastolic function was suboptimal and vessel thickness was higher among IVF-ICSI offspring. Compared with the metabolism of naturally conceived offspring, IVF-ICSI offspring displayed comparable BMI, lower low-density lipoprotein cholesterol levels, and higher fasting insulin levels.

CONCLUSION(S)

Children conceived by IVF-ICSI manifested a minor yet statistically significant increase in blood pressure without the clustering of increased BMI or impaired lipid metabolism by early adulthood. Our findings indicate a risk of cardiovascular disease among IVF-ICSI offspring, which calls for longer-term follow-ups and further investigation.

Short and long term outcomes of children conceived with assisted reproductive technology

Despite their wide and global use, possible short and long-term effects of fertility treatments on children is not well-established. In this review, birth defects and perinatal complications and their relationship with assisted reproductive technology (ART), along with long-term effects of ART on cardiovascular system, metabolism, behavior, cognitive skills, and childhood cancers are discussed. Children conceived through ART are at increased risk for birth defects and perinatal complications such as preterm delivery, low birth weight and small for gestational age. Parental characteristics, underlying infertility etiology and ART procedures themselves may contribute to this. The long-term effects of ART are difficult to establish. Studies so far report that ART children have normal social, emotional, cognitive, and motor functions. Likewise, despite some minor inconsistencies in some studies, they do not seem to be at increased risk for childhood cancers. However, there are a number of studies that imply vascular system may be adversely affected by ART and its possible consequences should be further investigated with follow up studies. Large scale studies with long-term follow up periods are required to determine the effects of ART on conceived children.

Obstetric and perinatal outcomes after either fresh or thawed frozen embryo transfer: an analysis of 112,432 singleton pregnancies recorded in the Human Fertilisation and Embryology Authority anonymized dataset

OBJECTIVE

To explore obstetric and perinatal outcomes in singleton pregnancies occurring as a result of fresh and thawed frozen embryo transfer using anonymized Human Fertilisation and Embryology Authority data.

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

Singleton births after IVF/intracytoplasmic sperm injection cycles in the United Kingdom (1991-2011).

INTERVENTION(S)

A total of 112,432 cycles (95,911 fresh and 16,521 frozen) were analyzed using multivariate logistic regression to explore associations between type of embryo transferred (frozen vs. fresh) and obstetric and perinatal outcomes. Relative risks (RRs) and their 99.5% confidence intervals (CIs) were calculated using Stata 14 MP, adjusting for potential confounders.

MAIN OUTCOME MEASURE(S)

Birth weight.

RESULT(S)

The adjusted RR (99.5% CI) of low birth weight [0.73 (0.66-0.80)] and very low birth weight [0.78 (0.63-0.96)] were all lower after frozen embryo transfer; however, RR of having a high birth weight baby was higher [1.64 (1.53-1.76)]. There was no difference in RR of preterm birth [0.96 (0.88-1.03)], very preterm birth [0.86 (0.70-1.05)], and congenital anomalies [0.86 (0.73-1.01)].

CONCLUSION(S)

The findings of low birth and very low birth weight after thawed frozen embryo transfer are consistent with the literature and provide reassurance regarding the outcome of pregnancies after frozen embryo transfers. However, they highlight the possibility of high birth weight in these babies. Because these results are based on observational data, further evidence from randomized, controlled trials is needed before elective cryopreservation of all embryos is practiced in preference to the current practice of transfer of fresh embryos.

Serum 25-hydroxyvitamin D concentrations and treatment outcomes of women undergoing assisted reproduction

BACKGROUND

Vitamin D deficiency impairs fertility in animal models, but the role of vitamin D in human fertility or treatment of infertility is less clear.

OBJECTIVE

We examined the association between circulating 25-hydroxyvitamin D [25(OH)D] concentrations and the outcome in women undergoing assisted reproduction technologies (ARTs).

DESIGN

We randomly selected 100 women undergoing infertility treatment with ART enrolled in an ongoing prospective cohort study who underwent 168 treatment cycles. Serum 25(OH)D concentrations were measured in samples collected from women between days 3 and 9 of gonadotropin treatment. Generalized linear mixed models were used to evaluate the association of 25(OH)D concentrations with ART outcomes while adjusting for potential confounders and accounting for repeated treatment cycles per woman.

RESULTS

Median (range) serum 25(OH)D concentrations were 86.5 (33.5-155.5) nmol/L. Ninety-one percent of participants consumed multivitamins. Serum 25(OH)D concentrations were positively related to fertilization rate. The adjusted fertilization rate for women in increasing quartiles of serum 25(OH)D were 0.62 (95% CI: 0.51, 0.72), 0.53 (95% CI: 0.43, 0.63), 0.67 (95% CI: 0.56, 0.76), and 0.73 (95% CI: 0.63, 0.80), respectively (P-trend = 0.03). This association persisted when analyses were restricted to women with serum 25(OH)D between 50 and 125 nmol/L when models were further adjusted for season of blood draw and when analyses were restricted to the first treatment cycle. However, 25(OH)D concentrations were unrelated to probability of pregnancy (P-trend = 0.83) or live birth after ART (P-trend = 0.47).

CONCLUSION

Vitamin D may be associated with higher fertilization rates, but this apparent benefit does not translate into higher probability of pregnancy or live birth. This trial was registered at www.clinicaltrials.gov as NCT00011713.

Methods for a Retrospective Population-based and Clinic-based Subfertility Cohort Study: the Fertility Experiences Study

BACKGROUND

Most cohort-based research for subfertility has been conducted in clinic-based cohorts, which may differ from population-based cohorts.

METHODS

We retrospectively recruited parallel cohorts of subfertile women: one by sampling two specialty fertility clinics in Utah, and one by population-based sampling based on marriage and birth records. The index date (of first clinic visit or subfertility status) was between 2000 and 2009, and we linked the women recruited to subsequent birth certificate records through December 2010.

RESULTS

We enrolled 459 women through clinic-based sampling and 501 women through population-based sampling. Clinic-based women were older, had higher annual household income and more likely to have had a most intensive treatment of intrauterine insemination (31%) or in vitro fertilisation (46%) than women from population recruitment (19% and 14% respectively). Conversely, they were less likely to have received no medical treatment (9%) compared to women from population recruitment (41%). For both types of sampling, prior to eligibility screening, non-responders were less likely to link to a live birth than responders: 51% vs. 58% for clinic-based, and 69% vs. 76% for the population-based with an index date in 2004.

CONCLUSIONS

Population-based sampling for subfertility cohort research identifies women who were more likely to have had less intensive treatment or no treatment. However, in both clinic-based and population-based sampling, women who have had a live birth are more likely to respond to retrospective recruitment.

Risks of spontaneously and IVF-conceived singleton and twin pregnancies differ, requiring reassessment of statistical premises favoring elective single embryo transfer (eSET)

A published review of the literature by Dutch investigators in 2004 suggested significant outcome differences between spontaneously - and in vitro fertilization (IVF) - conceived singleton and twin pregnancies. Here we review whether later studies between 2004-2015 confirmed these findings. Though methodologies of here reviewed studies varied, and all were retrospective, they overall confirmed results of the 2004 review, and supported significant outcome variances between spontaneously- and IVF-conceived pregnancies: IVF singletons demonstrate significantly poorer and IVF twins significantly better perinatal outcomes than spontaneously conceived singletons and twins, with differences stable over time, and with overall obstetrical outcomes significantly improved. Exaggerations of severe IVF twin risks are likely in the 50 % range, while exaggerations of milder perinatal risks are approximately in 25 % range. Though elective single embryo transfers (eSET) have been confirmed to reduce pregnancy chances, they are, nevertheless, increasingly utilized. eSET, equally unquestionably, however, reduces twin pregnancies. Because twin pregnancies have been alleged to increase outcome risks in comparison to singleton pregnancies, here reported findings should affect the ongoing discussion whether increased twin risks are factual. With no risk excess, eSET significantly reduces IVF pregnancy chances without compensatory benefits and, therefore, is not advisable in IVF, unless patients do not wish to conceive twins or have medical contraindications to conceiving twins.

Epigenetics and assisted reproductive technologies

Epigenetic modification controls gene activity without changes in the DNA sequence. The genome undergoes several phases of epigenetic programming during gametogenesis and early embryo development, coinciding with assisted reproductive technologies (ART) treatments. Imprinting disorders have been associated with ART techniques, but disentangling the influence of the ART procedures per se from the effect of the reproductive disease of the parents is a challenge. Epidemiological human studies have shown altered birthweight profiles in ART compared with spontaneously conceived singletons. Conception with cryopreserved/thawed embryos results in a higher risk of large-for-gestational-age babies, which may be due to epigenetic modification. Further animal studies have shown altered gene expression profiles in offspring conceived by ART related to altered glucose metabolism. It is controversial whether human adolescents conceived by ART have altered lipid and glucose profiles and thereby a higher long-term risk of cardiovascular disease and diabetes. This commentary describes the basic concepts of epigenetics and gives a short overview of the existing literature on the association between imprinting disorders, epigenetic modification and ART.

Fertility treatments and adverse perinatal outcomes in a population-based sampling of births in Florida, Maryland, and Utah: a cross-sectional study

OBJECTIVE

To investigate perinatal outcomes associated with fertility treatments, including assisted reproductive technology (ART), intrauterine insemination with ovulation stimulation (IUI), and ovulation stimulation alone (OS).

DESIGN

Population-representative cross-sectional survey of women with live births, 2004-2008.

SETTING

Florida, Maryland, and Utah, USA.

SAMPLE

21 803 women, weighted to represent 1 022 597 women.

METHODS

Survey and birth certificate data were analysed with logistic regression models adjusted for age, education, race, income, and parity, using separate models for singletons and all births. We used two referent groups: (1) women who never used fertility treatment and (2) subfertile women conceiving without treatment.

MAIN OUTCOME MEASURES

Preterm birth (<37 weeks), very preterm birth (<34 weeks), low birthweight (<2500 g), and very low birthweight (<1500 g).

RESULTS

Referent group 1: In singletons, ART was associated with preterm birth (OR 3.28; 95% CI 1.74, 6.20) and low birthweight (OR 2.91; 95% CI 1.99, 4.26). OS was also associated with low birthweight (OR 1.62; 95% CI 1.19, 2.19). Including all births, treatment was associated with preterm birth and low birthweight: ART (OR 6.21; 95% CI 4.21, 9.16 and OR 6.51; 95% CI 4.85, 8.73); IUI (OR 2.10; 95% CI 1.24, 3.56 and OR 2.41; 95% CI 1.54, 3.76); OS (OR 1.40; 95% CI 1.01, 1.94 and OR 2.10; 95% CI 1.60, 2.75), respectively. Referent group 2: ART was associated with both outcomes in all births, but not singletons.

CONCLUSIONS

Preterm birth and low birthweight associated with fertility treatments are largely attributable to multiple gestation, but are also related to underlying subfertility.

TWEETABLE ABSTRACT

Preterm birth is associated with subfertility, and with fertility treatments through multiple gestation.