Miscarriage

Miscarriage is spontaneous pregnancy loss before 20 weeks in Australia/NZ (loss after this is a stillbirth). Avoid the terms “spontaneous abortion”, “biochemical pregnancy”, and “blighted ovum” — imprecise and distressing.

Early miscarriage before 14 weeks affects 10–25% of known pregnancies, and about 80% of all pregnancy losses happen in that window. The lifetime risk of a miscarriage is nearly 25%, and risk rises with maternal age — by 40, up to half of pregnancies may end in miscarriage.

• Incomplete: partial loss of pregnancy tissue, moderate-severe bleeding ± visible tissue, usually with pain.
• Missed: embryo/fetus has died but tissue hasn’t passed — may be asymptomatic, found incidentally on a routine scan.
• Threatened: bleeding ± cramping with an otherwise-viable ongoing pregnancy.
• Recurrent: 2 or more losses up to 20 weeks (not 3 — ESHRE 2022/RANZCOG 2025 both use this threshold now), consecutive or not. RCOG still uses three or more first-trimester losses, but there is limited evidence that outcomes differ between two and three losses.

Assessment

• Confirm intrauterine location and viability with TV ultrasound (± serial β-hCG if location unclear — see Ectopic Pregnancy for pregnancy-of-unknown-location work-up).
• Non-viable pregnancy criteria: no fetal heartbeat with CRL ≥7mm, or no yolk sac in a gestational sac ≥25mm. Below these thresholds, rescan in 1 week before declaring non-viability.
• Take a group and antibody screen if not already done.

Use clear, empathetic language, and give information on what to expect, support services, follow-up and bereavement counselling. Offer information on pregnancy tissue management, including the option of returning the tissue to the woman and her family.

Management — incomplete or missed miscarriage

Offer a choice of expectant, medical, or surgical management to clinically stable women with no complications — discuss benefits/harms/patient preference for each.

Expectant: appropriate if haemodynamically stable, no infection, willing to wait ≥2 weeks (can take up to 4) with regular follow-up and support.

Medical:

Type	Regimen
Missed miscarriage	Mifepristone 200mg oral, then misoprostol 600microg (sublingual/buccal) or 800microg (vaginal/buccal/sublingual) 24–48h later. If bleeding hasn’t started 24–48h after the misoprostol, repeat doses of 400microg may be given.
Incomplete miscarriage	Misoprostol 600microg (sublingual/buccal) or 800microg (vaginal/buccal/sublingual) alone — no mifepristone needed. Repeat 400microg doses if bleeding hasn’t started at 24–48h.

(Mifepristone+misoprostol for missed miscarriage is an off-label indication under the Australian therapeutic goods framework.)

Surgical: suction aspiration (including manual) is preferred — avoid sharp curettage/D&C, which carries a higher risk of intrauterine adhesions (worse again with repeat D&C or repeat miscarriage). Antibiotic prophylaxis is recommended for surgical management (no specific agent proven best; most trial evidence used single-dose doxycycline ± metronidazole, ideally 2 hours pre-procedure).

Recurrent miscarriage

For most recurrent miscarriages no causative factor is found — say so upfront. Counsel about the benefits and harms of knowing a test result before ordering the panel.

Routinely recommended screening tests (RANZCOG 2025):

• Lupus anticoagulant, and anti-cardiolipin antibodies (IgG and IgM)
• 3D ultrasound
• TSH, TPO antibodies and thyroid function

Case-by-case: anti-β2-glycoprotein I, parental peripheral blood karyotyping, sperm DNA fragmentation, ANA (diagnostic purposes only).

Not routinely recommended: HLA/cytokine/NK cell testing; inherited thrombophilia screening (factor V Leiden, prothrombin gene mutation, protein S/C, antithrombin, MTHFR); fasting insulin/glucose and PCOS work-up; prolactin; ovarian reserve; androgens; vitamin D; LH; homocysteine.

Cytogenetic analysis of pregnancy tissue is not routinely recommended — genetic abnormalities are no more common in recurrent than sporadic miscarriage, and the result rarely changes management of the next pregnancy.

Antiphospholipid syndrome: offer low-dose aspirin 75–150 mg daily (from before pregnancy or from a positive test) plus low-molecular-weight heparin from a positive pregnancy test until at least 34 weeks, stopping before birth.

Thyroid: offer levothyroxine for overt hypothyroidism. There is insufficient evidence to offer it for subclinical hypothyroidism (including TSH >2.5 mIU/L), and it should not be offered where TSH is ≤2.5 mIU/L with positive thyroid autoantibodies. If untreated, check TSH at 7–9 weeks in the next pregnancy.

Uterine anomalies: septum resection is not recommended; surgery for other congenital malformations, caesarean niche resection, adhesiolysis, polypectomy and myomectomy are case-by-case decisions, not routine.

Threatened miscarriage — progesterone

• No previous miscarriage, or only 1: progesterone supplementation is not recommended — no difference in live birth/stillbirth/preterm birth rates.
• 2 or more previous miscarriages, with current bleeding: progesterone probably increases live birth rate — recommended. Vaginal micronised progesterone 400mg twice daily, continued to 16 weeks’ gestation. No excess congenital anomalies or serious adverse events.
• 2 or more previous miscarriages, no bleeding (asymptomatic): progestogens are not recommended — no benefit shown in the absence of bleeding.

Anti-D — changed 2025

Routine Rh D testing and anti-D immunoglobulin are no longer recommended for non-sensitised Rh D-negative women with threatened miscarriage or miscarriage before 10 weeks’ gestation — insufficient evidence it reduces sensitisation risk at this early, low-fetomaternal-haemorrhage stage. Beyond this (later gestation, or any surgically managed miscarriage), anti-D is still appropriate. Dose: 250 IU of anti-D immunoglobulin up to 12 weeks, 625 IU beyond 12 weeks.

Other presentations

• Molar pregnancy (~1:1200): refer to early pregnancy assessment/gynaecology. Complete mole = trophoblast-only overgrowth; partial mole = dispermic fertilisation, fetal tissue may be present but abnormal.
• Pregnancy of unknown location: no intrauterine pregnancy seen on scan despite a positive test — differential includes early IUP, complete/incomplete miscarriage, or ectopic. Serial β-hCG 48h apart (rise ≥63% suggests viable IUP, fall ≥50% suggests miscarriage — atypical patterns raise suspicion of ectopic); repeat scan when levels exceed the discriminatory zone or in 1 week.
• Retained products of conception: manage as for incomplete miscarriage (expectant/ medical); consider surgical referral if severe pain, heavy bleeding, or AP diameter of retained tissue >20mm on scan.

Referral and follow-up

• Arrange routine gynaecology referral for recurrent miscarriage investigation once a woman has had 2 or more losses.
• Prolonged (>3 weeks) bleeding after miscarriage: consider STI screening, infection work-up, and ultrasound if retained products are suspected.
• Advise women wanting to conceive again that they can start trying once ready — waiting a full cycle is not required by current evidence, though many practitioners still advise deferring ~1 month for dating clarity in the next pregnancy.