Trends in the incidence, rate and treatment of miscarriage-nationwide register-study in Finland, 1998-2016

STUDY QUESTION

What changes have occurred in the incidence of miscarriage, its treatment options, and the profile of the women having miscarriages in Finland between 1998 and 2016?

SUMMARY ANSWER

The annual incidence of registry-identified miscarriage has declined significantly between 1998 and 2016, and non-surgical management has become the dominant treatment.

WHAT IS KNOWN ALREADY

Miscarriage occurs in 8-15% of clinically recognized pregnancies and in ~30% of all pregnancies. Increasing maternal age is associated with an increasing risk of miscarriage. The treatment of miscarriage has evolved significantly in recent years: previously, surgical evacuation of the uterus was the standard of care, but nowadays medical and expectant management are increasingly used.

STUDY DESIGN, SIZE, DURATION

We conducted a nationwide retrospective cohort study of 128 381 women that had experienced a miscarriage that was managed in public healthcare between 1998 and 2016 in Finland.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used the National Hospital Discharge Registry for the data. Women aged 15-49 years that had experienced their first miscarriage during the follow-up period and had miscarriage-related diagnoses during their admission to public hospital were included in the study. Miscarriages were defined by the 10th Revision of the International Statistical Classification of Diseases and related Medical Problems (ICD-10) diagnostic codes O02*, O03* and O08*. Women with ectopic, molar and continuing pregnancies and induced abortions were excluded. Treatment was divided into surgical and non-surgical treatment using the surgical procedure codes.

MAIN RESULTS AND THE ROLE OF CHANCE

The annual incidence of registry-identified miscarriage has declined from 6.8/1000 15-49-year-old women in 1998 to 5.0/1000 in 2016 (P < 0.001). Also, the incidence rate of registry-identified miscarriage (i.e. the proportion of miscarriages of registry-identified pregnancies [i.e. deliveries, induced abortions, and miscarriages]) has declined from 112/1000 15-49-year-old pregnant women in 1998 to 83/1000 in 2016 (P < 0.001). The largest decrease in this proportion occurred among women over 40 years of age, among whom 26.5% of registry-identified pregnancies in 1998 ended in miscarriage compared to that of 16.4% in 2016. The proportion of missed abortion has increased (30.3 to 38.8%, P < 0.001) whereas that of blighted ovum has decreased (25.4 to 12.8%, P < 0.001). The proportion of registry-identified miscarriages seen among nulliparous women has increased from 43.7 to 49.6% (P < 0.001). Mean age at the time of miscarriage remained at 31 years throughout the study. Altogether, 29% of all miscarriages were treated surgically and 71% underwent medical or expectant management. The proportion of surgical management has decreased from 38.0 to 1.6% for spontaneous abortion, from 60.7 to 9.4% for blighted ovum and 70.9 to 11.2% for missed abortion between 1998 and 2016.

LIMITATIONS, REASONS FOR CAUTION

This study includes only women with registry-identified pregnancies, i.e. women who were treated in public hospitals. However, the number of women treated elsewhere is presumed to be small. Neither can this study estimate the number of women having spontaneous miscarriage with no hospital contact.

WIDER IMPLICATIONS OF THE FINDINGS

Both the annual incidence and incidence rate of miscarriage of all registry-identified pregnancies has decreased, and non-surgical management has become the standard of care. These findings are of value when planning allocation of healthcare resources and at individual level considering fertility and miscarriage questions. We speculate that improving ultrasound diagnostics explains the increasing proportion of missed abortion relative to other types of miscarriage. More investigation is needed to examine potential risk factors, complications and morbidity associated with miscarriages.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the research funds of the Helsinki and Uusimaa hospital system, by a personal grant from Viipurin Tuberkuloosisäätiö to R.L. and by a personal grant from The Finnish Cultural Foundation to N.H. The authors have no conflicts of interest to declare.

Development of Reference Materials for Paralytic Shellfish Poisoning Toxins

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained &lt;0.07 mg saxitoxin·2HCl/kg and 1.59 ± 0.20 mg decarbamoyl-saxitoxin·2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained &lt;0.07 mg saxitoxin·2HCl/kg and &lt;0.04 mg decarbamoyl-saxitoxin·2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 ± 1.2 μg/g.

[The content of biogenic amines in canned fish from the Turkish market]

This paper describes the determination of biogenic amines in a number of canned fish of the Turkish market by means of HPLC. Over all 39 cans of sardine, tuna, sardel, mackerel, pelamide and trout were tested. The determination of agmatine, cadaverine, histamine, putrescine and tyramine was performed by HPLC with post column derivatization with ortho-phthaldialdehyde. Four samples contained higher amounts of biogenic amines (three sardine samples contained more than 1000 mg/kg histamine) while all other samples were acceptable. These results demonstrate the need of instrumental analyses in the quality control system of Turkish producers of canned fish. The quality of the products at least of some producers has to be improved, e.g. by cooperation between the official food control and the quality assurance system of the producers.

[Electron spin resonance spectroscopy investigations of fresh fruit. Evidence of treatment with ionizing radiation]

This paper describes the development of a method for the identification of irradiated fresh fruits by measurement of the e.p.r. spectra of pips, kernels or stones. Measurement parameters were optimized and the irradiation specific spectrum was assigned to a cellulose radical by comparison with the e.p.r. spectrum of pure cellulose. Several fruits especially different varieties of strawberries were examined giving the following results: Detectable minimum doses were between 0.4 kGy and 0.9 kGy and the intensity of the irradiation specific signals was found to be linear up to doses of 11 kGy. The lifetime of the specific radicals (at room temperature and at deep freezing temperatures) was long enough compared to the storage time of fresh fruits. Additional information about the nature of the unspecific central signal was gained measuring the samples which were stored at different temperatures. The main conclusion of this study is that the e.p.r. method seemes to be well suited for the use in routine control and should be tested in an intercomparison to establish a routine method for the identification of irradiated fresh fruits.

[Electron spin resonance measurements on dried fruit. Carbohydrate composition and ESR signal structure of irradiated fruit]

While in a previous work the ESR spectroscopic detection of irradiated dried fruits was reported, in this paper liquid chromatographic determination of the carbohydrate fraction of these fruits is introduced and connected with the ESR results. After irradiation of dried fruits three different types of ESR spectra are observed. In most cases the dried fruits can be attached to these various types by means of their sugar composition. It was also found that the ESR spectra observed for sucrose-rich fruits are very similar to that of pure sucrose. The structure of the ESR spectra can change with storage. Probably, radical rearrangement reactions in the samples are responsible for these changes.

Evaluation of a gas chromatographic method to identify irradiated chicken, pork, and beef by detection of volatile hydrocarbons

A method suitable for routine application was used in an interlaboratory study to detect irradiation treatment of chicken carcass, pork, and beef. By using gas chromatographic analysis, 17 participating laboratories determined the quantity of 4 different radiation-induced volatile hydrocarbons (tetradecene, pentadecane, hexadecadiene, and heptadecene) in the fat fraction of coded specimens approximately 3 and 6 months after irradiation. The specimens of each type of meat were supplied by 2 different producers. The dose range tested (0.6-7.5 kGy) included levels commercially used to reduce the number of contaminating microorganisms (1-5 kGy). The method employed permitted a correct identification of irradiated or nonirradiated in 98.3% of the 864 specimens.

[ESR and HPLC studies of the detection of gamma irradiation of eggs]

Two methods for the identification of irradiated eggs are presented. Electron spin resonance (ESR) detects radiation-specific radicals in the calcite matrix of eggshells. ESR gives unequivocal results for doses clearly below the technologically relevant dose. The stability of the radical in the calcite matrix was tested over a period of 6 weeks. Products that contain no or only low amounts of fat but a high percentage of protein can be identified by HPLC. Only in the chromatograms of irradiated samples is a peak of the amino acid ortho-tyrosine present. This HPLC method may be of great interest especially for the identification of irradiated pasteurized liquid egg white.

[Identification of irradiated pasteurized egg products: a combined method for use in routine control]

Pasteurized egg products (whole egg, egg yolk and egg white) were tested for irradiation treatment in the German food control laboratories in Oldenburg/Niedersachsen and Kassel/Hessen as well as in the food irradiation laboratory of the German federal health office. Gas chromatographic/mass spectrometric measurements on the fat components of egg-products showed clearly whether the product had been irradiated or not. While in unirradiated samples no traces of special hydrocarbons (according to the fatty acid composition of egg) and no traces of the irradiation-specific compound 2-Dodecyl-cyclobutanone were found, irradiated control samples as well as products of two Belgian suppliers contained these substances. Additionally, regarding the rather high time consumption of gas chromatography, electron spin resonance (ESR)-measurements were carried out on the packaging material of egg products. Irradiated packaging material (cellulose) could be easily detected by the appearance of a signal pair in the ESR spectrum (cellulose radical). ESR measurements are very fast and easy to perform so that this method can be used for screening. Microbiological investigations showed remarkably reduced total numbers of microorganisms for some irradiated samples, but the microbiological status is influenced by other factors like storage-time and -temperature, so that microbiological tests can not be used successfully for screening on irradiation treatment.

Detection of irradiated food--methods and routine applications

Irradiation of food for the purpose of extension of shelf life, control of microbial load, reduction of pathogenic microorganisms and disinfection is regarded by many consumers with suspicion. One reason is the lack of methods within food-controlling laboratories which can detect irradiation treatment and which are applied to control correct labelling. This review describes the potential of various methods to reveal irradiation treatment. Special emphasis is given to the three most successful methods, thermoluminescence, electron spin resonance spectroscopy and detection of volatiles. The possibilities and limitations of applying the methods in routine control are discussed.

[Electron spin resonance spectroscopy as probes for spices. Detection of treatment with ionizing radiation]

Detection of irradiated spices by electron spin resonance (ESR) measurements was not successful in the past because a central line of unknown origin was detected in the ESR-spectra of both irradiated and unirradiated samples. Identification of irradiated samples by measuring the increase of intensity of this signal after irradiation is limited because the signal intensity decreases over a period of some weeks of storage and reaches the range of unirradiated samples. By changing the measurement conditions (low microwave power) we could detect two additional lines on both sides of the main signal. This line pair appears only in the spectra of irradiated spices. A similar line pair was found in the spectra of irradiated nutshells and possibly derives from cellulose radicals in the sample. For some spices, especially paprika, the identification of irradiated samples by detecting these additional lines was possible even after relatively long periods of storage.