About me

I am interested in the causes and consequences of reproductive challenges. The vast majority of my work is collaborative, involving individual experts and working in teams and larger networks.

Research description

Reproduction is the beginning of life, and the time we spend in utero inarguably the most important developmental period of our lives. Disruptions or insults during this critical time could, through direct or downstream effects, impair offspring health both in the short and long-term. My research spans across the whole the range of sensitive periods, from pre-conception through pregnancy up to labour and delivery, and concerns the health of both mother and child. 

Infertility and fertility treatments 

Involuntary childlessness is prevalent and increasing in many countries, and approximately 5% of births in the Nordic countries were conceived with assisted reproductive techniques. The potential consequences on maternal and offspring health are still not fully known, due to lingering methodological issues but also limited large-scale long-term follow-up. Rigorous evaluation is required to establish whether potential adverse effects are due to the treatments or rather their indication (and associated risk factors). In the last years we have looked into the long-term health of children conceived with ART, contributing also to an international collaborative effort to do so across several countries (LIFT Study), and we are currently moving to evaluate the impact of ART on women's cardiovascular health.

I am also involved in UppStART - the "Uppsala-Stockholm Assisted Reproductive Techniques study" is a prospective cohort study of couples undergoing infertility treatment (specifically IVF or ICSI) in the greater Stockholm and Uppsala municipalities. Participants were recruited from three of the four fertility and reproductive health clinics in Stockholm and one clinic in Uppsala, which also serves a large volume of patients from Stockholm.

Prescribed drug use 

Studies of the safety of prescribed drug use are similarly challenged by the need to disentangle the treatment effect from the role of the underlying condition (confounding by indication). Collaborative efforts to study offspring health following maternal use of psychotropics in pregnancy are currently undergoing substantial upscaling to allow the study of both safety and effectiveness of various prescribed drugs in pregnancy, using more advanced and detailed exposure characterisation and a new register linkage with maximised follow-up. In this I am particularly interested in the extension to evaluate what influence prescribed drug use can have on the ability to conceive and maintain pregnancy among women receiving fertility assistance.

Family designs

To make meaningful inference from observational data, and ultimately identify modifiable risk factors, it is vital to understand and address threats to study validity and in particular the influence of confounding. In my thesis work I used twins to exclude the potentially confounding influence of shared genetic and environmental factors on well-established associations between birth weight and adult health outcomes such as cardiovascular disease and breast cancer. I have since then moved to use siblings and other relatives to understand the influence of factors shared in families. While the ability to target otherwise unmeasured confounding is an attractive feature that has to be balanced against specific assumptions and limitations, and I am proud to contribute to an effort to identify, formalise and contextualise this in a series of methods papers on the sibling comparison design. 


Academic positions

Postdoc research fellow (2011-2016), Harvard T.H. Chan School of Public Health 

Assistant professor (2016-2020), Karolinska Institutet

Adjunct assistant professor (2016-2021), Harvard Chan School

Principal investigator (2020-), Karolinska Institutet

Adjunct associate professor (2022-2027), Harvard Chan School


Current supervision

Mina Rosenqvist, assistant professor MEB, KI (2020-)

Cina Nyberg, PhD-student Kliniska Vetenskaper DS, KI (2020-)

Angelo Mezzoiuso, MEB, KI (2022-)

Anne Brynolf, PhD-student KEP, KI (co-advisor 2019-)

Pauline De Corte. PhD-student, Charité Universitätsmedizin Berlin (co-advisor 2021-)

Mujin Ye, PhD-student, Onk-Pat KI (co-advisor 2022-)

Emma Cleary, PhD-student, Indiana University (co-advisor, 2022-)

Jennifer Yo, MPH-student, Harvard T.H. Chan School of Public Health (2022-)

Tilda Agild, MD-student, KI (Fall 2022)

Astrid Östholm, MD-student, KI (Fall 2022)


Previously supervised students

Chen Wang, PhD-student MEB, KI (2017-2022)

Ayesha Sujan, PhD-student, Indiana University (co-advisor)

Kelsey Wiggs, PhD-student, Indiana University (co-advisor)

Medical Degree Project at Karolinska Institutet: Davide Attebrant-Sbrzesny (17’), Eva Skärby (18’), Linnea Lin (19’), Theo Ekholm, Julius Martin and Edwin Råsberg (20’)

MPH Practicum at Harvard Chan School of Public Health: Rossana Calderon and John Lowery (19’), Mausumi Das, Anuj Pareek and Alexandra Puchwein-Schwepcke (20’), Matthew Carawana (21’), Daniel Rolnik (22')



National Institutes of Health, Forte, the Swedish Research Council, Fulbright, Karolinska Institutet, Lennander’s stiftelse, Wallenius’ stiftelse, and Iris.


Select publications 

Infertility and fertility treatments

Psychiatric disorders in children and adolescents conceived by assisted reproductive techniques: A nationwide study with 25 years of follow-up. Wang C, Johansson ALV, Rodriquez-Wallberg KA, Landén M, Almqvist C, Hernandez-Diaz S, Oberg AS. JAMA Psychiatry 2022 Feb 1;72(2):133-142. PMID: 34910092

ART, ADHD and School Performance. Wang C, Johansson A, Rodriguez-Wallberg K, Almqvist C, Hernandez-Diaz S, Oberg A.S. Pediatrics 2021 Jul;148(1):e2020033183. PMID: 34172555

Cohort Profile: The Uppsala-Stockholm Assisted Reproductive Techniques (UppStART) study. Iliadou AN, Oberg AS, Pege J, Rodriquez-Wallberg K, Olofsson JI, Wramsby H, et alBMJ Open 2019 Aug 28;9(8):e028866. PMID: 31467051

Pregnancy complications following fertility treatment-disentangling the role of multiple gestation. Oberg AS, VanderWeele TJ, Almqvist C, Hernandez-Diaz S. Int J Epidemiol 2018 08;47(4):1333-1342

Prescribed drug use in pregnancy

A nation-wide Swedish study of opioid analgesic prescribing patterns during pregnancy and associated pre-existing mental health conditions. Sujan A.C, Quinn P.D, Rickert M.E, Wiggs K.K, ..., Oberg A.S., D’Onofrio B.M. The Journal of Maternal-Fetal & Neonatal Medicine 2021 Jan 13;1-7. PMID: 33350491

Anti-seizure Medication Use During Pregnancy and Risk of ASD and ADHD in Children. Wiggs K.K, Sujan A.C, Rickert M.E, Quinn P.D, ..., Oberg A.S, D’Onofrio B.M. Neurology 2020 Dec 15;95(24):e3232-e3240. PMID: 33115775

A Population-based study of concurrent prescriptions of opioid analgesic and selective-serotonin reuptake inhibitor medications during pregnancy and risk for adverse birth outcomes. Sujan A.C, Rickert M.E, Quinn P.D, Ludema C, ..., Oberg A.S, D’Onofrio B.M. Paediatric and Perinatal Epidemiology 2020 Mar;35(2):184-193. PMID: 33441038

Maternal prescribed opioid analgesic use during pregnancy and associations with adverse birth outcomes: A population-based study. Sujan AS, Quinn PD, Rickert ME, Wiggs KK, ..., Oberg AS, D’Onofrio BM. PLoS Med. 2019 Dec 2;16(12):e1002980. PMID: 31790390

Relation of in-utero exposure to antiepileptic drugs to pregnancy duration and size at birth. Margulis A, Hernandez-Diaz S, McElrath T, Rothman KJ, Plana E, ..., Oberg AS. PLoS One 2019 Aug 5;14(8):e0214180. PMID: 31381574

Associations of Maternal Antidepressant Use During the First Trimester of Pregnancy With Preterm Birth, Small for Gestational Age, Autism Spectrum Disorder, and Attention-Deficit/Hyperactivity Disorder in Offspring. Sujan AC, Rickert ME, Oberg AS, Quinn PD, Hernández-Díaz S, Almqvist C, et al. JAMA 2017 04;317(15):1553-1562. PMID: 28418479

Family designs 

Sibling comparison studies. Sjolander A, Frisell T, Oberg AS. Annual Review of Statistics and Its Application 2021 Oct 21 Online review in advance of Vol 9 publication in March 2022.

Accounting for confounding in observational studies. D’Onofrio BM, Sjolander A, Lichtenstein P, Lahey B, Oberg AS. Annual Review of Clinical Psychology 2020 May 16(1):25-48. PMID: 32384000

Translational Epidemiologic Approaches to Understanding the Consequences of Early-Life Exposures. D'Onofrio BM, Class QA, Rickert ME, Sujan AC, Larsson H, Kuja-Halkola R, Oberg AS. Behavior Genetics 2016 05;46(3):315-28. PMID: 26590988

Carryover Effects in Sibling Comparison Designs. Sjölander A, Frisell T, Kuja-Halkola R, Oberg S, Zetterqvist J.Epidemiology 2016 11;27(6):852-8. PMID: 27488059

Sibling comparison designs: bias from non-shared confounders and measurement error. Frisell T, Öberg S, Kuja-Halkola R, Sjölander A. Epidemiology 2012 Sep;23(5):713-20. PMID:22781362

Causal interpretation of between-within models for twin studies. Sjölander A, Frisell T, Oberg S. Epidemiologic Methods2012 Aug;1(1): 217–237.

Outcome-dependent associations between short interpregnancy interval and offspring psychological and educational problems: a population-based quasi-experimental study. Class QA, Rickert ME, Larsson H, Oberg AS, Sujan AC, Almqvist C et alInt J Epidemiol 2018 08;47(4):1159-1168. PMID: 29566153

Association of Labor Induction With Offspring Risk of Autism Spectrum Disorders. Oberg AS, D'Onofrio BM, Rickert ME, Hernandez-Diaz S, Ecker JL, Almqvist C, et al. JAMA Pediatrics 2016 09;170(9):e160965. PMID: 27454803. PMID: 29939263

Cancer risks in twins and singletons from twin and non-twin families. Chen L, Cnattingius S, Nyman Iliadou A, Oberg AS. Int. J. Cancer 2016 Mar;138(5):1102-10. PMID: 26414953

Genetic contribution to postpartum haemorrhage in Swedish population: cohort study of 466,686 births. Oberg AS, Hernandéz-Diaź S, Frisell T, Greene MF, Almqvist C, Bateman BT. BMJ 2014 Aug;349():g4984. PMID: 25121825

Maternal and fetal genetic contributions to postterm birth: familial clustering in a population-based sample of 475,429 Swedish births. Oberg AS, Frisell T, Svensson AC, Iliadou AN. Am. J. Epidemiol. 2013 Mar;177(6):531-7. PMID: 23425630

Birth weight predicts risk of cardiovascular disease within dizygotic but not monozygotic twin pairs: a large population-based co-twin-control study. Oberg S, Cnattingius S, Sandin S, Lichtenstein P, Iliadou AN. Circulation 2011 Jun;123(24):2792-8. PMID: 21632494


Oberg AS. Health Consequences of Adverse Fetal Growth – Studies in Twins. Doctoral Thesis Karolinska Institutet, 2011. IBAN: 978-91-7457-371-8.

Teaching portfolio

Instructor in Analytic Methods for Epidemiologists, Harvard Chan School 2016 -

Shared course instructor in Epidemiology I, Karolinska Institutet 2020 -

Lecturer [Causal mediation analysis] in Epidemiology III, Karolinska Institutet 2018 -

Grading instructor Systematic Reviews and Meta-analysis, Harvard Chan School 2016

Lecturer [Research synthesis] in Clinical Data Science, Harvard Medical School 2016


MD 2002, Karolinska Institutet

MPH 2009, Harvard T.H. Chan School of Public Health

PhD 2011. Karolinska Institutet

Docent 2020, Karolinska Institutet


Academic positions

Postdoc research fellow (2011-2016), Harvard T.H. Chan School of Public Health 

Assistant professor (2016-2020), Karolinska Institutet

Adjunct assistant professor (2016-2021), Harvard Chan School

Principal investigator (2020-), Karolinska Institutet

Adjunct associate professor (2022-2027), Harvard Chan School