Risk of borderline ovarian tumors after fertility treatment - Results from a Danish cohort of infertile women.

OBJECTIVE: Results from previous studies examining the association between fertility treatment and borderline ovarian tumors are inconsistent. The aim of this study was to investigate the association between fertility treatment and borderline ovarian tumors in a cohort of infertile women. METHODS: This cohort study was based on the Danish Infertility Cohort and included all infertile women aged 20-45 years living in Denmark between 1 January 1995 and 31 December 2017 (n = 146,891). Information on use of fertility drugs, borderline ovarian tumors and cancer diagnoses, covariates, emigration, and vital status was obtained by linkage to national registers. Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) with adjustment for potential confounders for overall borderline ovarian tumors and for serous- and mucinous borderline ovarian tumors separately. RESULTS: During a median 11.3 years of follow-up, 144 women developed a borderline ovarian tumor. No marked associations between ever use of clomiphene citrate, gonadotropins, gonadotropin-releasing hormone receptor modulators, human chorionic gonadotropin or progesterone and borderline ovarian tumors were observed, neither overall nor for serous and mucinous borderline ovarian tumors analysed separately. Further, no clear associations with borderline ovarian tumors were found according to cumulative dose, time since first use or parity status for any fertility drugs. CONCLUSIONS: No marked associations between use of fertility drugs and borderline ovarian tumors were observed. However, the cohort's relatively young age at end of follow-up emphasizes the importance of extending the follow-up period for women who have used fertility drugs.

Maternal use of hormonal contraception and risk of childhood autism spectrum disorders: A Parental Exposures and Child Health (PECH) cohort study.

A recent hypothesis suggests that maternal hormonal contraception use has contributed to the increasing incidence of autism spectrum disorders (ASD). We used a nationwide population-based cohort (the PECH cohort) including 1,056,149 Danish children born in the period January 1, 1998, to December 31, 2014, to assess associations between maternal hormonal contraception use and childhood ASD (end of follow-up: December 31, 2017). Maternal hormonal contraception use was grouped as "recent use" (≤ 3 months before pregnancy start or during pregnancy), "previous use" (>3 months before pregnancy start) and "never use", except for few products. Incidence rate ratios (IRRs) were estimated using Poisson regression. During follow-up of nearly 12 million person-years, 19,996 children were diagnosed with ASD. A slightly higher IRR was observed for maternal recent use of any hormonal contraception, compared to previous use. This association was largely driven by the non-oral progestin-only products, and associations were especially seen for infantile autism and other/unspecified ASD. An increased IRR of infantile autism was also observed for recent use of the oral progestin-only products, compared to previous use. Our results suggest that maternal use of hormonal contraception may be associated with ASD risk in children, especially for the progestin-only products.

In Utero Exposure to Hormonal Contraception and Mortality in Offspring with and without Cancer: A Nationwide Cohort Study.

Approximately 400 million women of reproductive age use hormonal contraceptives worldwide. Eventually, pregnancy sometimes occurs due to irregular use. Use in early pregnancy is found to be associated with child morbidities including cancer, the main reason for disease-related death in children. Here, we add the missing piece about in utero exposure to hormonal contraception and mortality in offspring, including assessments of prognosis in children with cancer. In utero exposure to hormonal contraception may be associated with death since we found a hazard ratio (HR) of 1.22 (95% confidence interval (CI) 1.01-1.48) compared to children of mothers with previous use. The HRs were 1.22 (95% CI 0.99-1.13) for oral combined products and 2.92 (95% CI 1.21-7.04) for non-oral progestin-only products. A poorer prognosis was also found in exposed children with leukemia (3.62 (95% CI: 1.33-9.87)). If causal, hormonal contraception in pregnancy seems detrimental for offspring health and a marker of poorer prognosis in children with leukemia.

Effects of early maternal cancer and fertility treatment on the risk of adverse birth outcomes.

Background: Early maternal cancer and fertility treatment each increase the risk for adverse birth outcomes, but the joint effect of these outcomes has not yet been reported. Thus, the aim was to assess the individual and joint effect of maternal cancer and fertility treatment on the risk for adverse birth outcomes. Methods: This population-based cohort study included 5487 live-born singletons identified in the Danish Medical Birth Register (1994-2016) of mothers with previous cancer (<40 years) recorded in the Danish Cancer Registry (1955-2014). We randomly selected 80,262 live-born singletons of mothers with no cancer <40 years matched to mothers with cancer by birth year and month. We calculated odds ratios (ORs) for preterm birth, low birth weight (LBW) (<2500 g) and small for gestational age (SGA), mean differences in birth weight in grams, and additional cases of preterm birth (gestational age<259 days) per 100,000 person-years. Multiplicative and additive interaction of maternal cancer and fertility treatment was compared with outcomes of children conceived naturally to mothers with no maternal cancer (reference group). Findings: Among 84,332 live-born singletons, increased ORs for preterm birth were observed among children born to mothers with previous cancer (1·48, 95% confidence interval [CI] 1·33-1.65) or after fertility treatment (1·43, 95% 1·28-1-61), with 22 additional cases of preterm birth among both group of children (95% CI 15-29; 95% CI 14-30). In the joint analyses, the OR for SGA for children born after fertility treatment to mothers with previous cancer was similar to that of the reference group (OR 1·02, 95% CI 0·72-1·44, P for interaction=0·52). Children with both exposures had increased ORs for LBW (1·86, 95% CI 1·17-2·96, P for interaction=0·06) and preterm birth (2·31, 955 CI 1·66-3·20, P for interaction = 0·56), with 61 additional cases of preterm birth (95% CI 27-95, P for interaction=0.26) over that of children in the reference group. The mean birth weight was also lower in children born to mothers with both exposures (-140 g, 95% CI -215; -65) (P for interaction=0.06) but decreased to -22 g (95% CI -76; 31) after adjustment for GA. Interpretation: Although we did not find any statistically significant additive interaction between maternal cancer and fertility treatment, children born after fertility treatment of mothers with previous cancer were at increased risk for adverse birth outcomes. Thus, pregnant women with both exposures need close follow-up during pregnancy. Funding: The Danish Cancer Society and the Danish Childhood Cancer Foundation.

Association Between Maternal Hormonal Contraception Use and Central Nervous System Tumors in Children.

Importance: The incidence of central nervous system (CNS) tumors in children appears to be increasing, yet few risk factors are established. There is limited information regarding whether maternal hormonal contraception use increases this risk. Objective: To examine the association between maternal hormonal contraception use and CNS tumors in children (<20 years). Design, Setting, and Participants: In this nationwide cohort study based on population-based registry data, 1 185 063 children born in Denmark between January 1, 1996, and December 31, 2014, were followed up for a diagnosis of a CNS tumor (final follow-up on December 31, 2018). Exposures: Maternal hormonal contraception use was analyzed according to any use, regimen (combined/progestin only), and route of administration (oral/nonoral), categorized as recent use (≤3 months before start and during pregnancy), previous use (>3 months before start of pregnancy), and no use. For injections, implants, and intrauterine devices that are used for a different time period, the categorization was appropriately altered. Main Outcomes and Measures: Hazard ratio (HR) and incidence rate difference (IRD) of CNS tumors diagnosed at younger than 20 years. Results: After 15 335 990 person-years of follow-up (mean follow-up, 12.9 years), 725 children were diagnosed with a CNS tumor. The mean age at diagnosis was 7 years, and 342 (47.2%) of the diagnosed children were female. The adjusted incidence rate of CNS tumors per 100 000 person-years was 5.0 for children born to mothers with recent hormonal contraception use (n = 136 022), 4.5 for children born to mothers with previous use (n = 778 843), and 5.3 for children born to mothers with no use (n = 270 198). The corresponding HRs were 0.95 ([95% CI, 0.74-1.23]; 84 children with CNS tumors; IRD, -0.3 [95% CI, -1.6 to 1.0]) for recent use and 0.86 ([95% CI, 0.72-1.02]; 421 children with CNS tumors; IRD, -0.8 [95% CI, -1.7 to 0.0]) for previous use, compared with no use. No statistically significant associations were found for recent or previous use of oral combined, nonoral combined, oral progestin only, or nonoral products compared with no use of hormonal contraception. Conclusions and Relevance: Among Danish children, there was no statistically significant association between any maternal hormonal contraception use and CNS tumor risk.

Prenatal exposure to nitrofurantoin and risk of childhood leukaemia: a registry-based cohort study in four Nordic countries.

BACKGROUND: Studies have suggested increased risks of childhood leukaemia after prenatal exposure to antibiotics, particularly nitrofurantoin. However, these findings may be related to the underlying maternal infection. This multinational study aimed to investigate the association between prenatal nitrofurantoin exposure and childhood leukaemia while accounting for maternal infection. METHODS: In a population-based cohort study of children born in Denmark, Finland, Norway or Sweden from 1997 to 2013, prenatal exposure to nitrofurantoin or pivmecillinam (active comparator) was ascertained from national Prescription Registries. Childhood leukaemia was identified by linkage to national Cancer Registries. Poisson regression was used to estimate incidence rate ratios (IRRs) and incidence rate differences (IRDs) with inverse probability of treatment weights applied to account for confounding. RESULTS: We included 44 091 children prenatally exposed to nitrofurantoin and 247 306 children prenatally exposed to pivmecillinam. The children were followed for 9.3 years on average (standard deviation 4.1). There were 161 cases of childhood leukaemia. The weighted IRR for prenatal nitrofurantoin exposure when compared with pivmecillinam was 1.34 (95% confidence interval 0.88, 2.06), corresponding to an IRD of 15 per million person-years. Higher point estimates were seen for first- and third-trimester exposure. There was no evidence of a dose-response relationship. CONCLUSIONS: Prenatal exposure to nitrofurantoin was not substantially associated with childhood leukaemia, although a slightly elevated IRR with confidence intervals including the null was observed, corresponding to a small absolute risk. The lack of a dose-response relationship and a clear biological mechanism to explain the findings suggests against a causal association.

Hospital Contacts for Psychiatric Disorders in Parents of Children With Cancer in Denmark.

Background: Having a child diagnosed with cancer is a devastating experience that may affect parents' mental health. We aimed to assess the risk of hospital contacts for psychiatric disorders in parents of children with cancer. Methods: We conducted a nationwide population-based cohort study using Danish registry data. Parents of children diagnosed with cancer between 1982 and 2014 (n = 6689 mothers, n = 5509 fathers) were matched with comparison parents of cancer-free children (n = 67 544 mothers, n = 55 756 fathers). We used Cox proportional hazards models to estimate the risk of hospital contacts for any psychiatric disorder and specific disorders. Cox models were also used to investigate sociodemographic and cancer-related risk factors for psychiatric disorders. Results: Incidence rates of hospital contacts for any psychiatric disorder were 426 per 100 000 person-years in mothers of children with cancer and 345 per 100 000 person-years in comparison mothers. For fathers, the respective incidence rates were 260 and 262 cases per 100 000 person-years. Compared with parents of cancer-free children, mothers of children with cancer were at an increased risk of hospital contacts for any psychiatric disorder (hazard ratio = 1.23, 95% confidence interval = 1.12 to 1.36), whereas no elevated risk was seen in fathers (hazard ratio = 0.99, 95% confidence interval = 0.87 to 1.13). Among mothers, risks were particularly elevated for affective and stress-related disorders. Parents of deceased children and children diagnosed at a younger age were at particular risk of hospital contacts for psychiatric disorders. Conclusion: Hospital contacts for psychiatric disorders were overall rare. Health-care professionals should draw attention to subgroups of vulnerable parents to meet their needs of support and adequate treatment.

Maternal Medication Use and Childhood Cancer in Offspring-Systematic Review and Considerations for Researchers.

Cancer is an important cause of childhood mortality, yet the etiology is largely unknown. A combination of pre- and postnatal factors is thought to be implicated, including maternal medication use. We aimed to provide: 1) a systematic review of peer-reviewed publications on associations between maternal medication use and childhood cancer, with a focus on study design and methodology; and 2) suggestions for how to increase transparency, limit potential biases, and improve comparability in studies on maternal medication use and childhood cancer. We conducted a systematic search in the PubMed, Embase, Scopus, Cochrane, and Web of Science databases to June 8, 2020. Altogether, 112 studies were identified. The reviewed studies were heterogeneous in study design, exposure, and outcome classification. In 21 studies (19%), the outcome was any childhood cancer. Of the 91 papers that reported on specific types of cancer, 62% did not report the cancer classification system. The most frequently investigated medication groups were sex hormones (46 studies, excluding fertility medications), and antiinfectives (37 studies). Suggestions for strengthening future pharmacoepidemiologic studies on maternal medication use and childhood cancer relate to choice of cancer classification system, exposure windows, and methods for identification of, and control for, potential confounders.

Maternal use of hormonal contraception and risk of childhood ADHD: a nationwide population-based cohort study.

Although maternal use of hormones has been suspected of increasing the risk for childhood attention-deficit/hyperactivity disorder (ADHD), no study has examined hormonal contraception use in this context. We examined the association between maternal hormonal contraception use before or during pregnancy and ADHD risk in children. This nationwide population-based cohort study included 1,056,846 children born in Denmark between 1998 and 2014. Prescriptions for hormonal contraceptives redeemed by the mother was categorized as: no use, previous use (> 3 months before pregnancy), and recent use (≤ 3 months before or during pregnancy). Children were followed for ADHD, from birth until 31 December 2015. Cox proportional hazard models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). During 9,819,565 person-years of follow-up (median: 9.2), ADHD was diagnosed or a prescription for ADHD medication redeemed for 23,380 children (2.2%). The adjusted HR for ADHD was higher in children of mothers who had previously (HR 1.23; 95% CI 1.18-1.28) or recently (HR 1.30; 95% CI 1.24-1.37) used hormonal contraception than in those of mothers with no use. The highest estimates were seen for use of non-oral progestin products with HRs of 1.90 (95% CI 1.59-2.26) for previous use, 2.23 (95% CI 1.96-2.54) for recent use, and 3.10 (95% CI 1.62-5.91) for use during pregnancy. Maternal use of hormonal contraception was associated with an increased risk for ADHD in the offspring; more pronounced for non-oral progestin-only than other products.

Ninth-grade school achievement in Danish children conceived following fertility treatment: a population-based cohort study.

OBJECTIVE: To assess whether academic achievement among children conceived following fertility treatment is different from that of children born to fertile women while also considering the underlying infertility. DESIGN: Population-based cohort study. SETTING: Denmark. PATIENT(S): The study population consisted of all 154,536 firstborn, live-born, singleton children in Denmark between 1995 and 2000 who completed their ninth grade with an examination. INTERVENTION(S): The Danish Infertility Cohort was used to identify children conceived after fertility treatment (n = 10,099), and information on mean school marks was obtained from Statistics Denmark. MAIN OUTCOME MEASURE(S): Linear regression models were used to estimate mean differences (MDs) and 95% confidence intervals (CIs). Multiple logistic regression models were used to estimate odds ratios (OR) and 95% CI of not passing the ninth-grade examination. RESULTS: The crude overall mean marks for children conceived after the various fertility treatment procedures were in general higher than in children born to fertile women. However, after adjustment for potential confounders, the overall mean marks were statistically significantly lower for children conceived after the various fertility treatment procedures (e.g., any fertility treatment: MD -0.13; 95% CI -0.18, -0.08) compared with children born to fertile women. Further, children conceived after any fertility treatment had a statistically significant lower crude likelihood of not passing the ninth-grade examination (OR 0.66; 95% CI 0.53, 0.81) compared with children born to fertile women, whereas no difference was observed in the confounder adjusted analyses (OR 1.15; 95% CI 0.89, 1.49). When children born to women requiring fertility assistance but without fertility treatment in the index pregnancy were used as a reference group, no differences in the adjusted overall mean marks and the likelihood of not passing the ninth grade with an examination were observed. CONCLUSION: Our findings indicate that fertility treatment per se is not associated with lower school marks and the likelihood of not passing the ninth grade with an examination. Hence, we suggest that factors related to both fertility problems and cognitive development may more likely explain the slightly lower academic performance (i.e., modest lower mean marks) among children conceived after fertility treatment.

The impact of childhood cancer on parental separation, divorce, and family planning in Denmark.

BACKGROUND: Childhood cancer is a devastating experience for the family. The objective of the current study was to assess the impact of having a child with cancer on parental separation, divorce, and future family planning among families residing in Denmark. METHODS: The authors conducted a nationwide cohort study using Danish registry data. Parents of children diagnosed with cancer between 1982 and 2014 (7066 children and 12,418 case parents) were matched with 10 comparison parents of cancer-free children per case parent (69,993 children and 125,014 comparison parents). We used discrete-time Cox regression models to compare the risk of separation (end of cohabitation) and divorce between case and comparison parents, and to identify risk factors for separation and divorce among case parents only. Descriptive statistics were used to compare family planning between case and comparison parents. RESULTS: Case parents were found to have a slightly lower risk of separation (hazard ratio, 0.96; 95% confidence interval, 0.93-0.99) and divorce (hazard ratio, 0.92; 95% confidence interval, 0.87-0.97) than comparison parents. The authors found that case parents who were aged <45 years, with short education (an International Standard Classification of Education code indicating early childhood education, primary education, and lower secondary education), and who were unemployed were at an increased risk of separation and divorce. Moreover, the parents of children diagnosed with cancer at a young age (aged <15 years) were more likely to separate or divorce. No differences with regard to the total number of children and time to a next child after the cancer diagnosis were observed between case and comparison parents. CONCLUSIONS: Having a child with cancer was not associated with an overall adverse impact on parents' risk of separation or divorce and future family planning. These encouraging findings should be communicated to parents to support them along their child's cancer trajectory.

Incidence and time trends of childhood cancer in Denmark, 1943-2014.

Background: Surveillance of childhood cancer incidence is informative for etiologic research and health policy. However, high-quality data covering several decades of virtually complete cancer diagnosis in children is sparse.Methods: Incident cases of childhood cancer (0-19 years at diagnosis), classified according to Birch and Marsden's International Classification of Childhood Cancer, first edition (ICCC-1), were identified in the Danish Cancer Registry and used to calculate age-standardized incidence rates (ASRs) and estimated annual percentage change (EAPC) separately for 1943-1977 (early period) and 1977-2014 (recent period).Results: During 1943-2014, 15,184 childhood cancer cases were reported. The ASR for any cancer was 13.0 per 100 000 person-years in the early period (EAPC 0.55%; 95% CI 0.30-0.80) and 17.7 per 100 000 person-years in the recent period (EAPC 1.16%; 95% CI 0.96-1.36). In both periods, the increasing trend was seen in both boys (EAPC 0.69%; 95% CI 0.43-0.96/EAPC 0.96%; 95% CI 0.75-1.17) and girls (EAPC 0.37%; 95% CI -0.01-0.75/EAPC 1.41%; 95% CI 1.11-1.72) and in children aged 0-14 years (EAPC 0.53%; 95% CI 0.26-0.80/EAPC 0.86%; 95% CI 0.64-1.08) and 15-19 years (EAPC 0.60%; 95% CI 0.19-1.02/EAPC 1.97%; 95% CI 1.67-2.28). Increasing trends were observed for all main diagnostic groups.Conclusions: The incidence of childhood cancer in Denmark has increased since the 1940s, especially since 1977 and in older children. In recent years the increase has been most pronounced among girls.

Risk of febrile seizures among children conceived following fertility treatment: A cohort study.

BACKGROUND: Studies have shown that fertility treatment in mothers is associated with neurological problems in children. However, knowledge about any association between maternal use of fertility treatment and febrile seizures in children is lacking. OBJECTIVE: To determine whether maternal use of fertility treatment is associated with febrile seizures in children. METHODS: All liveborn children in Denmark during 1996-2012 (n = 1 065 901) were linked with the Danish Infertility Cohort and the Danish national registers and were followed from one year of age until the first episode of a febrile seizure, death, emigration, loss to follow-up, or end of follow-up (December 2015). Cox proportional hazard regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with adjustment for potential confounders. RESULTS: Approximately 16% children (n = 172 140) were conceived by infertile women, and approximately 3% (n = 34 082) were diagnosed with febrile seizures during follow-up. Compared with children conceived by fertile women, children conceived following any fertility treatment (HR 1.11, 95% CI 1.06, 1.16), following specific fertility treatment, for example IVF (HR 1.15, 95% CI 1.05, 1.25), ICSI (HR 1.20, 95% CI 1.10, 1.32), and following fertility drugs (HR 1.06, 95% CI 1.00, 1.11) had slight increase in risk of febrile seizures, after adjusting for calendar year of birth, parental age, education, parity status, and maternal smoking during pregnancy. The associations were unchanged when children conceived naturally by infertile women were used as the reference group. CONCLUSIONS: Children conceived following fertility treatment had slightly increased relative risk for febrile seizures.

The impact of childhood cancer on parental working status and income in Denmark: Patterns over time and determinants of adverse changes.

Having a child with cancer may affect the socioeconomic situation of the parents. We aimed to assess the impact of childhood cancer on parental working status and income and to identify determinants of adverse changes after the child's cancer diagnosis by calendar period. We conducted a nationwide cohort study using Danish registry data. Parents of children diagnosed with cancer in 1982-2014 (n = 12,418) were matched with comparison parents of cancer-free children (n = 125,014). We analysed annual working status (working/not working) and annual disposable income (lowest quintile/not lowest quintile) of case and comparison parents over a period of 10 years after diagnosis by calendar period (1982-1999 vs. 2000-2014). Logistic regression models were used to identify determinants of adverse changes after diagnosis. Mothers of children diagnosed in 1982-1999 were more likely not working or having a low income than comparison mothers up to 10 years after diagnosis. This risk of not working or low income was lower in mothers of children diagnosed in 2000-2014 compared to 1982-1999 in the first years after diagnosis (pinteraction < 0.05). We observed no consistent patterns among fathers. Low parental education, diagnosis of lymphoid leukaemia and younger age of the child at diagnosis were the main determinants of adverse changes in working status or income after diagnosis. Childhood cancer adversely interfered with parents' socioeconomic situation in the earlier calendar period, particularly among mothers. The absence of such an effect in more recent years emphasises the supportive role of a countries' welfare system alongside the general advances in childhood cancer treatment.

Association Between Fertility Treatment and Cancer Risk in Children.

Importance: An increasing number of children worldwide are born after the use of fertility treatment, although it remains unclear whether the treatment affects the risk of childhood cancer and whether any associations observed are due to the use of specific drugs, the use of specific procedures, or the underlying infertility. Objective: To examine the association between different types of fertility treatments and cancer risk in children. Design, Setting, and Participants: A retrospective cohort study based on Danish population-based registry data and the Danish Infertility Cohort (individual record linkage) that included 1 085 172 children born in Denmark between January 1, 1996, and December 31, 2012, linked with parental information. There were a total of 2217 children diagnosed with cancer (follow-up occurred during 1996-2015). Exposures: Maternal fertility treatment during the index pregnancy, including the use of fertility drugs (clomiphene [n = 33 835], gonadotropins [n = 57 136], gonadotropin-releasing hormone analogs [n = 38 653], human chorionic gonadotropin [n = 68 181], progesterone [n = 41 628], and estrogen [n = 16 948]) and assisted reproductive technology (in vitro fertilization [n = 19 448], intracytoplasmic sperm injection [n = 13 417], and frozen embryo transfer [n = 3356]). Each exposure was examined separately and compared with children born to fertile women. Main Outcomes and Measures: Hazard ratios and incidence rate differences for childhood cancer. Results: After 12.2 million person-years of follow-up (mean, 11.3 years), the incidence rate of childhood cancer was 17.5 per 100 000 for children born to fertile women (n = 910 291) and 44.4 per 100 000 for children born after the use of frozen embryo transfer (n = 3356). Compared with children born to fertile women, the use of frozen embryo transfer was associated with an elevated risk of childhood cancer (14 cancer cases; hazard ratio, 2.43 [95% CI, 1.44 to 4.11]; incidence rate difference, 26.9 [95% CI, 2.8 to 51.0] per 100 000), mainly due to an increased risk of leukemia (5 cancer cases; incidence rate, 14.4 per 100 000; hazard ratio, 2.87 [95% CI, 1.19 to 6.93]; incidence rate difference, 10.1 [95% CI, -4.0 to 24.2] per 100 000) and sympathetic nervous system tumors (<5 cancer cases; hazard ratio, 7.82 [95% CI, 2.47 to 24.70]). There were no statistically significant associations with the use of the other types of fertility treatment examined. Conclusions and Relevance: Among children born in Denmark, the use of frozen embryo transfer, compared with children born to fertile women, was associated with a small but statistically significant increased risk of childhood cancer; this association was not found for the use of other types of fertility treatment examined.